JP2021093705A - Microstrip antenna, microstrip antenna unit, and microstrip antenna unit group - Google Patents

Abstract

To improve radiation characteristics in a microstrip antenna that use a radiation element and a mesh-patterned conductor layer as a ground conductor.SOLUTION: A microstrip antenna (10) includes a radiation element (13) based on a conductor layer of a mesh pattern, and a ground conductor (12) composed of the conductor layer of the mesh pattern. The radiation element (13) is provided with a strip-shaped outer frame (131) that borders the first side to the third side (C1 to C3), and is composed of a conductor layer having lower electrical resistance than the main part of the radiation element (13).SELECTED DRAWING: Figure 1

Description

The present invention relates to a microstrip antenna, a microstrip antenna unit, and a group of microstrip antenna units.

A microstrip antenna is known as an aspect of an antenna whose operating band is a band to which electromagnetic waves called microwaves and millimeter waves belong. The microstrip antenna has a dielectric substrate, a radiation element obtained by patterning a conductor layer formed on one main surface of the substrate, and a conductor layer formed on the other main surface of the substrate. It is provided with a ground conductor obtained by patterning. The ground conductor is formed in a region including a radiating element when viewed in a plan view.

By the way, as the frequency of electromagnetic waves increases from microwaves to millimeter waves, it becomes difficult for electromagnetic waves to be diffracted. Therefore, when mobile communication is performed using millimeter waves, it may be difficult to communicate between the base station and the mobile terminal in an area shielded by an obstacle such as a building. Such areas are called dead zones. In order to eliminate such a dead zone, attempts have been made to attach a microstrip antenna to the window glass of a high-rise building as a relay antenna.

However, a microstrip antenna in which each of the radiating element and the ground conductor is composed of a solid pattern conductor layer does not have translucency. Therefore, such a microstrip antenna becomes conspicuous when attached to a window glass, which may spoil the aesthetic appearance of a high-rise building. The solid pattern conductor layer means a conductor layer having no openings and no translucency.

Japanese Unexamined Patent Publication No. 2001-11328

Patent Document 1 describes a microstrip antenna that employs a conductor layer having a mesh pattern as at least one of a radiating element and a ground conductor. A plurality of openings are regularly formed in the conductor layer of the mesh pattern. Therefore, by adopting a conductor layer having a mesh pattern as the radiating element and the ground conductor, it is possible to provide a microstrip antenna having translucency. That is, it is possible to provide a microstrip antenna that is inconspicuous even when attached to a window glass.

However, as described above, a plurality of openings are regularly formed in the conductor layer of the mesh pattern. Therefore, when the thickness of the conductor layers is the same, the electric resistance in the conductor layer of the mesh pattern exceeds the electric resistance in the conductor layer of the solid pattern. Therefore, a microstrip antenna using a mesh pattern conductor layer as a radiating element and a ground conductor tends to have lower radiation characteristics than a microstrip antenna using a solid pattern conductor layer as a radiating element and a ground conductor.

One aspect of the present invention has been made in view of the above-mentioned problems, and an object thereof is a microstrip antenna, a microstrip antenna unit, and a microstrip antenna using a conductor layer of a mesh pattern as a radiation element and a ground conductor. It is to improve the radiation characteristics in the unit group.

In order to solve the above problems, the microstrip antenna according to the first aspect of the present invention is formed on a light-transmitting dielectric substrate and one main surface of the substrate, and has a mesh pattern. A radiating element that includes the main part composed of the conductor layer of the above and is rectangular when viewed in a plan view, and a region of the other main surface of the substrate that includes at least the radiating element when viewed in a plan view. The first side, which is one side of a rectangle formed on the same surface as the ground conductor including the main part formed of the conductor layer of the mesh pattern and circumscribing the radiating element and circumscribing the radiating element. On the side, one end is provided with a feeding line connected to the radiating element. In the first aspect, the radiating element is a conductor layer having a band-shaped outer frame that borders the radiating element at least along the first side and having a lower electric resistance than the main part of the radiating element. An outer frame composed of is provided.

When an radiating element whose circumscribing figure is rectangular when viewed in a plan view is excited by using a feeder connected to the radiating element on the first side of the rectangle, the current supplied to the radiating element from the feeder is used. Is easy to flow in the edge region along the four sides of the rectangular radiating element. In particular, among the edge regions along the four sides, the current easily flows through the edge region corresponding to the first side.

According to the above configuration, an outer frame formed of a conductor layer having a lower electrical resistance than the main portion of the radiating element is provided in an edge region corresponding to a first side in which a current easily flows. As a result, the electrical resistance of the outer frame is lower than that of the portion other than the outer frame using the conductor layer of the mesh pattern.

Therefore, in the first aspect, the radiation characteristics can be improved in a microstrip antenna including a radiation element and a ground conductor whose main part is composed of a conductor layer having a mesh pattern. In other words, the first aspect is a microstrip antenna that is inconspicuous even when attached to a window glass and has excellent radiation characteristics.

Further, in the microstrip antenna according to the second aspect of the present invention, in the first aspect described above, the outer frame includes at least the first side, the second side sandwiching the first side, and the second side. A configuration is adopted in which the radiating element is bordered along the third side.

According to the above configuration, in addition to the edge region corresponding to the first side where the current easily flows, the outer frame is also provided in the second side and the edge region corresponding to the third side where the current easily flows. ing. Therefore, the second aspect is a microstrip antenna that is inconspicuous even when attached to a window glass and has excellent radiation characteristics.

Further, in the microstrip antenna according to the third aspect of the present invention, in the second aspect described above, the outer frame is a band-shaped outer frame that borders the radiating element along all four sides of the rectangle. There is a configuration adopted.

According to the above configuration, since the radiating element is provided with an outer frame along all four sides, the microstrip including the radiating element and the ground conductor whose main part is composed of a conductor layer having a mesh pattern. In the antenna, the radiation characteristics can be further improved.

Further, in any of the above-mentioned first to third aspects, the microstrip antenna according to the fourth aspect of the present invention has one end of the radiating element on the first side of the outer frame. An inner frame formed of a conductor layer which is connected to a portion along the above and extended in a direction perpendicular to the first side and has a lower electric resistance than the main part of the radiating element. The configuration is adopted, which is further provided with.

According to the above configuration, by appropriately adjusting the number, width, and length of the inner frame, the capacitance generated between the radiating element and the ground conductor can be set to a desired value or approached to a desired value. Can be done.

Further, in the microstrip antenna according to the fifth aspect of the present invention, in any one of the first to fourth aspects described above, the width of the feeder line is the supply of the first side. A configuration is adopted in which the wire becomes thinner as it approaches the connection point to which it is connected.

According to the above configuration, the impedance matching between the feeder line and the radiating element can be improved by appropriately adjusting the width of the feeder line.

Further, the microstrip antenna according to the sixth aspect of the present invention is a connection in which the feeding line is connected among the first side in any one of the first to fifth aspects described above. A pair of notches are formed on both sides of the point.

According to the above configuration, the impedance matching between the feeder line and the radiating element can be improved by appropriately adjusting the shape and size of the pair of notches.

Further, the microstrip antenna according to the seventh aspect of the present invention has the first dielectric layer holding the radiating element and the ground conductor in any one of the first to sixth aspects described above. On the other main surface of the substrate, the second dielectric layer for fixing at least one of the first dielectric layer and the radiation element on one main surface of the substrate, and the first fixing member for fixing at least one of the radiation elements. A configuration is adopted in which the second dielectric layer and the second fixing member for fixing at least one of the ground conductors are further provided.

According to the above configuration, the microstrip antenna can be easily manufactured.

Further, the microstrip antenna unit according to the eighth aspect of the present invention is a microstrip antenna unit including a plurality of microstrip antennas according to any one of the first to seventh aspects described above. The configuration is adopted in which the substrate constituting each microstrip antenna is a single substrate.

According to the above configuration, the radiation characteristics can be further enhanced as compared with the microstrip antenna according to any one aspect of the present invention. Further, since each microstrip antenna is configured by using a single substrate, it becomes easy to align the directivity of each microstrip antenna or to control it.

Further, the microstrip antenna unit according to the ninth aspect of the present invention is the microstrip antenna unit according to the eighth aspect described above, and the plurality of microstrip antennas are located at positions corresponding to the respective apex of the rectangular shape. It is composed of the first to fourth microstrip antennas provided in the above, and has a first branch portion that combines the feeding lines of the first microstrip antenna and the second microstrip antenna into a first sub feeding line. , The second branch portion that combines the feeding lines of the third microstrip antenna and the fourth microstrip antenna into the second sub feeding line, and the first sub feeding line and the second sub feeding line are the main feeding lines. The distance from the first branch to the radiating element of the first microstrip antenna, the distance from the first branch to the radiating element of the second microstrip antenna, The distance from the second branch to the radiating element of the third microstrip antenna and the distance from the second branch to the radiating element of the fourth microstrip antenna are equal and from the third branch. The distance to the first branch portion and the distance from the third branch portion to the second branch portion are different.

According to the above configuration, when the distance from the third branch to the first branch and the distance from the third branch to the second branch are equal, that is, from the third branch to the first to fourth branches. The directivity of the microstrip antenna unit can be changed as compared with the case where the distances to the respective radiating elements of the microstrip antenna are equal. Therefore, the directivity of the microstrip antenna unit can be adjusted by adjusting the position of the third branch portion.

Further, the microstrip antenna unit according to the tenth aspect of the present invention is the spacer provided on one main surface side of the single substrate in the microstrip antenna unit according to the eighth or ninth aspect described above. However, a configuration is adopted in which the single substrate is further provided with a spacer for providing a predetermined distance between the single substrate and another structure.

According to the above configuration, when the microstrip antenna unit is installed near the surface of another structure, the microstrip antenna unit can be separated from the other structure by a predetermined distance. Therefore, by appropriately designing a predetermined distance, it is possible to suppress a decrease in radiation characteristics even when a conductor such as metal is present inside another structure.

Further, the microstrip antenna unit group according to the tenth aspect of the present invention is a microstrip antenna unit group including a plurality of microstrip antenna units according to the seventh to ninth aspects described above, and each microstrip antenna. The single substrate that makes up the unit adopts a configuration that is shared between each microstrip antenna unit.

According to the above configuration, a plurality of microstrip antenna units can be integrated by sharing a single substrate.

According to one aspect of the present invention, the radiation characteristics can be improved in a microstrip antenna using a conductor layer having a mesh pattern as a radiation element and a ground conductor.

(A) is a perspective view of the microstrip antenna according to the first embodiment of the present invention, and each of (b) and (c) is a plan view and a plan view of the microstrip antenna shown in (a), respectively. It is a bottom view. It is a top view which shows one aspect of the microstrip antenna shown in FIG. 1 (a). Each of (a) and (b) is a plan view of a first modification and a second modification of the microstrip antenna shown in FIG. 1, respectively. Each of (a) to (c) is a plan view of a third modification to a fifth modification of the microstrip antenna shown in FIG. 1, respectively. Each of (a) to (c) is a plan view of the sixth modification to the eighth modification of the microstrip antenna shown in FIG. 1, respectively. Each of (a) and (b) is a plan view and a cross-sectional view of the microstrip antenna module according to the second embodiment of the present invention, respectively. (A) is a graph showing the S-parameters of the microstrip antenna which is the first reference example and the first comparative example of the present invention. (B) is a plan view of a microstrip antenna which is a first comparative example of the present invention. It is a graph which shows the S parameter of the microstrip antenna which is the 1st reference example to the 3rd reference example of this invention. It is a graph which shows the S parameter of the microstrip antenna which is 1st Example to 3rd Example of this invention. (A) is a cross-sectional view of a part of the ninth modification of the present invention, and (b) is an enlarged cross-sectional view of a part of the ninth modification of the present invention. It is a top view of the microstrip antenna unit which concerns on 3rd Embodiment of this invention. It is a side view of the state in which the microstrip antenna unit shown in FIG. 11 is installed near the surface of the window glass. It is a top view of the microstrip antenna unit group which concerns on 4th Embodiment of this invention. Each of (a) and (b) is a graph showing the S-parameter S11 and the gain of the fourth embodiment and the second comparative example of the present invention, respectively. Each of (a) and (b) is a graph showing the S-parameter S11 and the gain of the fifth embodiment and the third comparative example of the present invention, respectively. Each of (a) and (b) is a graph showing the S-parameter S11 and the gain of the fifth embodiment group and the third comparative example group of the present invention, respectively. It is a graph which shows the gain of the 6th Example group and the 4th reference example group of this invention. It is a graph which shows the S parameter S11 and the gain of the 7th Example group of this invention. It is a graph which shows the S parameter S11 and gain of the 8th Example group of this invention.

[First Embodiment]
The microstrip antenna 10 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1A is a perspective view of the microstrip antenna 10, and each of (b) and (c) is a plan view and a bottom view of the microstrip antenna 10, respectively. In the present embodiment, the plan view of the radiating element 13 included in the microstrip antenna 10 is referred to as a plan view, and the plan view of the ground conductor 12 included in the microstrip antenna 10 is referred to as a bottom view. Further, the microstrip antenna 10', which is one aspect of the microstrip antenna 10, will be described with reference to FIG. FIG. 2 is a plan view showing one aspect of the microstrip antenna 10'.

By appropriately designing each design parameter, the microstrip antenna 10 can obtain good radiation characteristics with a band to which an electromagnetic wave called a microwave or a millimeter wave belongs as an operating band. The band used as the operating band of the microstrip antenna 10 is not limited as long as it is included in the band to which the electromagnetic wave called microwave or millimeter wave belongs. In the present embodiment, the operating band of the microstrip antenna 10 is assumed to be the 3.5 GHz band.

<Structure of microstrip antenna 10>
As shown in FIGS. 1A to 1C, the microstrip antenna 10 includes a substrate 11, a ground conductor 12, a radiation element 13, and a feeder line 14.

(Board 11)
The substrate 11 is made of a light-transmitting dielectric material. In this embodiment, an acrylic resin is used as the dielectric material constituting the substrate 11. However, the dielectric constituting the substrate 11 is not limited to this. The dielectric material constituting the substrate 11 may be appropriately selected in consideration of physical property values such as relative permittivity and dielectric loss tangent. Other examples of the dielectric constituting the substrate 11 include liquid crystal polymer (LCP) resin and glass. Further, as the substrate 11, a printed substrate using glass fiber reinforced plastic (GFRP, Glass Fiber Reinforced Plastic) can also be preferably used. The GFRP constituting the printed circuit board is not limited, and an example thereof includes a glass epoxy board (standard name is FR-4).

Of the pair of main surfaces constituting the substrate 11, one main surface (the main surface arranged on the upper side in (a) of FIG. 1) is referred to as the main surface 11a, and the other main surface ((a) of FIG. 1). The main surface) arranged on the lower side in)) is referred to as a main surface 11b.

(Ground conductor 12)
The ground conductor 12 is composed of a conductor layer having a mesh pattern. However, in one aspect of the present invention, at least the main portion of the ground conductor 12 may be composed of a conductor layer having a mesh pattern. In such a case, for example, the outer edge region of the ground conductor 12 may be composed of a solid pattern conductor layer or a conductor layer having an electric resistance equivalent to that of the solid pattern conductor layer.

In this embodiment, copper is used as the conductor constituting the ground conductor 12. However, the conductor constituting the ground conductor 12 is not limited to this. The conductor constituting the ground conductor 12 may be appropriately selected in consideration of conductivity, ease of processing, and the like. Other examples of conductors constituting the ground conductor 12 include metals having a low resistivity (for example, silver, aluminum, and gold). Further, the conductor constituting the ground conductor 12 may contain a dielectric material such as a resin or an organic solvent, such as a conductor paste.

In the present embodiment, the ground conductor 12 is a mesh pattern in which a plurality of openings that are square in a plan view are formed in a matrix (see (c) of FIG. 1), and the aperture ratio is 85%. The pattern is adopted. However, the mesh pattern adopted in the ground conductor 12 is not limited to this. The mesh pattern used in the ground conductor 12 may be appropriately selected in consideration of translucency (in other words, aperture ratio). For example, the shape of the plurality of openings in a plan view may be a circular shape or a regular hexagonal shape. Further, the aperture ratio can be appropriately selected depending on how inconspicuous it is and how much the sheet resistance of the ground conductor is set.

Further, the structure and manufacturing method of the conductor layer of the mesh pattern are not limited. For example, a mesh pattern conductor layer can be obtained by patterning a solid pattern conductor layer using a double-sided substrate in which a solid pattern conductor layer is formed on a pair of main surfaces of a dielectric substrate. The method for patterning the solid pattern conductor layer is not limited, but for example, a photolithography method can be preferably used. Further, the conductor layer of the mesh pattern can be drawn by using a conductor paste typified by silver paste or copper paste. Further, it can be appropriately selected from commercially available conductor layers having a mesh pattern.

As the aperture ratio of the mesh pattern is increased, the ground conductor 12 (as a result, the microstrip antenna 10) can be made less noticeable even when the mesh pattern is attached to a glass plate such as a window glass. On the other hand, the capacitance generated between the ground conductor 12 and the radiating element 13 may become small, and the radiating characteristics of the microstrip antenna 10 may deteriorate. In order to make the microstrip antenna 10 inconspicuous, the aperture ratio of the mesh pattern used in the ground conductor 12 is preferably 80% or more, and more preferably 90% or more. However, if the aperture ratio is made too large, the sheet resistance value of the mesh pattern becomes large, and it becomes difficult to obtain good radiation characteristics. In order to obtain good radiation characteristics, the sheet resistance value of the mesh pattern is preferably 1 Ω / sq or less, and more preferably 0.1 Ω / sq or less. In view of these conditions, when copper is used as the conductor constituting the ground conductor 12, the aperture ratio of the mesh pattern used in the ground conductor 12 is obtained in order to obtain good radiation characteristics while making the microstrip antenna 10 inconspicuous. Is preferably 80% or more and 90% or less.

In the present embodiment, the ground conductor 12 is formed on the entire surface of the main surface 11b of the substrate 11 as shown in FIG. 1 (c). On the other hand, the radiating element 13 described later is formed on a part of the main surface 11a of the substrate 11 as shown in FIG. 1B. Therefore, the ground conductor 12 is formed in a region including the radiating element when viewed in a plan view. As described above, the ground conductor 12 may be formed in a region including the radiating element when viewed in a plan view, and the shape and size of the region forming the ground conductor 12 can be appropriately designed.

The means for joining the main surface 11b and the ground conductor 12 to each other is not limited and may be appropriately selected.

When the microstrip antenna 10 is manufactured using a so-called double-sided plate in which a solid pattern conductor layer is formed on each of the main surfaces 11a and 11b of the substrate 11, the main surface 11b and the ground conductor 12 are separated by intermolecular force. It is joined. That is, there is no adhesive layer interposed between the main surface 11b and the ground conductor 12. In the present embodiment, the microstrip antenna 10 is illustrated assuming that the adhesive layer does not intervene between the main surface 11b and the ground conductor 12.

On the other hand, when the substrate 11 and the copper foil not bonded to the substrate 11 are used to manufacture the microstrip antenna 10, the ground conductor 12 of the mesh pattern is formed, and then the main surface 11b and the ground are used by using an adhesive layer. It may be joined to the conductor 12.

(Radiation element 13)
The radiating element 13 includes a main part and an outer frame 131. The main part (the part other than the outer frame 131) is composed of a conductor layer of a mesh pattern. In the present embodiment, as the conductor layer of the mesh pattern constituting the main part of the radiating element 13, the same conductor layer as the conductor layer of the mesh pattern constituting the ground conductor 12 is adopted as follows.

In the present embodiment, the radiating element 13 is a mesh pattern (see (b) of FIG. 1) in which a plurality of openings having a square shape in a plan view are formed in a matrix, and the aperture ratio is 85%. The pattern is adopted. However, the mesh pattern adopted in the radiating element 13 is not limited to this. The mesh pattern used in the radiating element 13 may be appropriately selected in consideration of translucency (in other words, aperture ratio). For example, the shape of the plurality of openings in a plan view may be a circular shape or a regular hexagonal shape. Further, the aperture ratio can be appropriately selected depending on how inconspicuous it is and how much the sheet resistance of the ground conductor is set.

Further, the structure and manufacturing method of the conductor layer of the mesh pattern are not limited. For example, a mesh pattern conductor layer can be obtained by patterning a solid pattern conductor layer using a double-sided substrate in which a solid pattern conductor layer is formed on a pair of main surfaces of a dielectric substrate. The method for patterning the solid pattern conductor layer is not limited, but for example, a photolithography method can be preferably used. Further, the conductor layer of the mesh pattern can be drawn by using a conductor paste typified by silver paste or copper paste. Further, it can be appropriately selected from commercially available conductor layers having a mesh pattern.

The larger the aperture ratio of the mesh pattern, the less noticeable the radiating element 13 (as a result, the microstrip antenna 10) can be even when the mesh pattern is attached to a glass plate such as a window glass. On the other hand, the capacitance generated between the ground conductor 12 and the radiating element 13 may become small, and the radiating characteristics of the microstrip antenna 10 may deteriorate. In order to make the microstrip antenna 10 inconspicuous, the aperture ratio of the mesh pattern used in the radiating element 13 is preferably 80% or more, and more preferably 90% or more. However, if the aperture ratio is made too large, the sheet resistance value of the mesh pattern becomes large, and it becomes difficult to obtain good radiation characteristics. In order to obtain good radiation characteristics, the sheet resistance value of the mesh pattern is preferably 1 Ω / sq or less, and more preferably 0.1 Ω / sq or less. In view of these conditions, when copper is used as the conductor constituting the radiation element 13, the aperture ratio of the mesh pattern adopted in the radiation element 13 is obtained in order to obtain good radiation characteristics while making the microstrip antenna 10 inconspicuous. Is preferably 80% or more and 90% or less.

As described above, the radiating element 13 is formed on a part of the main surface 11a of the substrate 11 (see (b) of FIG. 1). The means for joining the main surface 11a and the radiating element 13 to each other is not limited and may be appropriately selected. This point is the same as the joining of the main surface 11b and the ground conductor 12 described above. In the present embodiment, no adhesive layer is interposed between the main surface 11a and the radiating element 13.

In the present embodiment, the radiating element 13 is rectangular when viewed in a plan view. Therefore, when viewed in a plan view, the figure circumscribing the radiating element 13 is a rectangle. In the following, the rectangle circumscribing the radiating element 13 will be referred to as a rectangle C. In the case of this embodiment, since the radiating element 13 is rectangular, the radiating element 13 and the rectangle C are the same. In the rectangle C, the pair of long sides facing each other are referred to as sides C1 and C4, and the pair of short sides facing each other are referred to as sides C2 and C3. That is, the sides C2 and C3 sandwich the side C1. Each of the sides C1, C2, and C3 is an example of the first side, the second side, and the third side in the claims, respectively.

In this embodiment, the radiating element 13 is rectangular. However, in one aspect of the present invention, the radiating element 13 may have a rectangular shape. An example of the rectangular radiating element 13 is a rounded rectangle in which the four vertices of the rectangle are rounded. Further, another example of the rectangular radiating element 13 is a shape in which a notch is formed on any one of the sides C1 to C4. As described above, in one aspect of the present invention, even when the radiating element 13 has a rectangular shape, the figure circumscribing the radiating element 13 is rectangular.

Of the edge regions of the radiating elements 13 along the sides C1 to C4 of the rectangle C, the edge regions along the sides C1 to C3 are band-shaped outer frames 131 rimming the radiating elements 13 and are solid pattern conductors. An outer frame 131 composed of layers is provided. The solid pattern conductor layer forming the outer frame 131 is preferably made of the same conductor as the mesh pattern conductor layer forming the main part of the radiating element 13. That is, it is preferable that each of the portions of the outer frame 131 along the sides C1 to C3 and the main portion are integrally molded using a single conductor. In the present embodiment, the radiating element 13 is integrally molded with copper in both the main portion and the outer frame 131. Since the main part and the outer frame 131 are integrally molded, it is possible to reduce the resistance that may occur when the main part and the outer frame 131 are formed of separate conductors and are electrically connected to each other. The solid pattern conductor layer means a conductor layer having no openings and no translucency.

However, each of the portions along the sides C1 to C3 of the outer frame 131 and the main portion are each formed of separate conductors, and the radiating element 13 is formed by electrically connecting them. You may.

In the present embodiment, the outer frame 131 is provided so as to border the sides C1 to C3, but is not limited thereto. FIG. 2 shows a microstrip antenna 10', which is an aspect of the microstrip antenna 10. The microstrip antenna 10'is obtained by replacing the radiating element 13 included in the microstrip antenna 10 with the radiating element 13'. The outer frame 131'provided by the radiating element 13'is such that the radiating element 13'is bordered on the edge region along the side C1 of the edge regions of the radiating element 13' along the sides C1 to C4 of the rectangle C. It is provided in. As described above, in one aspect of the present invention, the radiating element 13'may be provided with a band-shaped outer frame 131'that borders the radiating element 13'at least along the side C1. In particular, if the outer frame 131'is provided so as to border the side C1 through which the current easily flows, the radiation characteristics can be sufficiently improved.

Further, in one aspect of the present invention, the radiating element 13 is a strip-shaped inner frame having one end connected to a portion of the outer frame 131 along the side C1 and extending in a direction perpendicular to the side C1 and is solid. An inner frame composed of a conductor layer of the pattern may be further provided. The number of inner frames is not limited, and may be one or a plurality of inner frames. These aspects of the present invention will be described later with reference to FIGS. 3 and 4.

In the present embodiment, the outer frame 131 is composed of a solid pattern conductor layer. However, the outer frame 131 is not limited to the solid pattern conductor layer. The outer frame 131 may be formed of a conductor layer having a lower electrical resistance than the main portion of the radiating element 13. For example, the outer frame 131 is a conductor layer in which a plurality of fine openings are formed in a matrix, and has a solid pattern. It can also be composed of a conductor layer having an electric resistance equivalent to that of the conductor layer. An example of a conductor layer in which a plurality of fine openings are formed in a matrix is a conductor layer having a mesh pattern, which is formed in a state where the line width is as close as possible to the pitch. According to this configuration, the main part of the radiating element 13 and the outer frame 131 can be formed by using the same forming process. This is because the only difference between the main part of the radiating element 13 and the outer frame 131 is the difference in the line width and pitch of the mesh pattern.

Further, in order to reduce the resistivity of the outer frame 131 as much as possible, it is preferable that the aperture ratio of the conductor layer in which a plurality of fine openings are formed in a matrix is as small as possible.

When the size of the plurality of fine openings is sufficiently small, the sheet resistance of the conductor layer in which the plurality of fine openings are formed in a matrix becomes a value close to that of the solid pattern conductor layer. Therefore, the microstrip antenna 10 exhibits good radiation characteristics even when the outer frame 131 is composed of a conductor layer in which a plurality of fine openings are formed in a matrix.

As an example of the electrical resistance of the conductor layer, a sheet resistance can be used. Further, the sheet resistance that can be regarded as equivalent to the solid pattern conductor layer is preferably 100 mΩ / sq or less, and more preferably 10 mΩ / sq or less. As will be described later, 1Ω / sq can be mentioned as an example of the sheet resistance of the conductor layer of the mesh pattern.

(Feed line 14)
The feeder line 14 is a strip-shaped conductor layer formed on the same surface as the radiating element 13, that is, on the main surface 11a. The feeder line 14 is composed of a solid pattern conductor layer. The solid pattern conductor layer forming the feeder line 14 is preferably made of the same conductor as the outer frame 131 of the radiating element 13. In the present embodiment, the feeder line 14 is made of the same copper as the main portion of the radiating element 13 and the outer frame 131. The feeder line 14 and the ground conductor 12 form a microstrip line.

The feeder line 14 extends in a direction orthogonal to the side C1 (that is, a direction parallel to the sides C2 and C3), and one end thereof is connected to the radiation element 13 on the side C1. In the present embodiment, the radiation element 13 and the feeder line 14 are integrally molded together. Therefore, there is no physical boundary between the radiating element 13 and the feeder line 14. In FIG. 1A, the virtual boundary between the outer frame 131 and the feeder line 14 is illustrated by a two-dot chain line. Moreover, the point on the virtual boundary is illustrated as a connection point CP. The connection point CP is an example of a connection point between the outer frame 131 and the feeder line 14.

In the present embodiment, the feeder line 14 is arranged so that the central axis (the axis that bisects the width direction of the feeder line 14) passes through the midpoint of the side C1. That is, the radiating element 13 and the feeder line 14 are configured to have a line-symmetrical shape with the central axis of the feeder line 14 as a symmetrical line in a plan view. However, in one aspect of the present invention, the feeder line 14 may be configured so that the central axis deviates from the midpoint of the side C1.

As with the outer frame 131, the feeder line 14 may be formed of a conductor layer having a lower electrical resistance than the main portion of the radiating element 13. Therefore, instead of the solid pattern conductor layer, it can be composed of a conductor layer in which a plurality of fine openings are formed in a matrix and has an electric resistance equivalent to that of the solid pattern conductor layer. According to this configuration, the main part and the outer frame 131 of the radiating element 13 and the feeder line 14 can be formed by using the same forming process.

<Effect of microstrip antenna 10>
As described above, in the microstrip antenna 10, the radiating element 13 is provided with an outer frame 131 which is a band-shaped outer frame 131 bordering the sides C1, C2, and C3 and is composed of a solid pattern conductor layer. ing.

When the radiating element 13 whose circumscribing figure is rectangular when viewed in a plan view is excited by using the feeder line 14, the current supplied from the feeder line 14 to the radiating element 13 is the rectangular C of the radiating elements 13. It is easy to flow in the edge region along the sides C1 to C4. In particular, among the edge regions along the four sides, the current easily flows through the edge regions corresponding to the side C1 to which the feeder line 14 is connected and the sides C2 and C3 sandwiching the side C1.

In the microstrip antenna 10, an outer frame 131 formed of a solid pattern conductor layer is provided in an edge region corresponding to sides C1 to C3 where a current easily flows. As a result, the electric resistance of the outer frame 131 is lower than the electric resistance of the main part of the radiating element 13 using the conductor layer of the mesh pattern.

Therefore, the microstrip antenna 10 can improve the radiation characteristics in the microstrip antenna 10 using the conductor layer of the mesh pattern as the radiation element 13 and the ground conductor 12. In other words, the microstrip antenna 10 is a microstrip antenna that is inconspicuous even when attached to a window glass and has excellent radiation characteristics.

<Modification example>
The first modification to the eighth modification of the microstrip antenna 10 will be described with reference to FIGS. 3 to 5. Each of (a) and (b) of FIG. 3 is a plan view of the microstrip antennas 10A and 10B which are the first modification and the second modification of the microstrip antenna 10, respectively. Each of (a) to (c) of FIG. 4 is a plan view of the microstrip antennas 10C, 10D, and 10E, which are the third modification to the fifth modification of the microstrip antenna 10, respectively. Each of (a) to (c) of FIG. 5 is a plan view of the microstrip antennas 10F, 10G, and 10H, which are the sixth modification to the eighth modification of the microstrip antenna 10, respectively.

Each of the microstrip antennas 10A to 10F can be obtained by replacing the radiating element 13 included in the microstrip antenna 10 with the radiating elements 13A to 13F, respectively. Therefore, in each of the microstrip antennas 10A to 10F, the same reference numerals are given to the substrate 11, the ground conductor 12 (not shown in FIGS. 2 to 5), and the feeder line 14 having the same configuration as the microstrip antenna 10. Use and do not repeat the description.

Further, the microstrip antenna 10G is obtained by replacing the feeder line 14 included in the microstrip antenna 10D with the feeder line 14G based on the microstrip antenna 10D. Similarly, the microstrip antenna 10H is obtained by replacing the feeder line 14 included in the microstrip antenna 10E with a feeder line 14H based on the microstrip antenna 10E.

(First modification and second modification)
The radiating element 13A included in the microstrip antenna 10A is obtained by further providing an inner frame 132A based on the radiating element 13 included in the microstrip antenna 10 (see FIG. 3A). The inner frame 132A is a strip-shaped conductor whose one end is connected to a portion of the outer frame 131A along the side C1 and the other end is open. The inner frame 132A is extended in a direction parallel to the sides C2 and C3, and the other end reaches the side C4. The inner frame 132A is composed of a solid pattern conductor layer like the outer frame 131A corresponding to the outer frame 131. In the microstrip antenna 10A, the inner frame 132A is arranged on an extension of the feeder line 14. Therefore, the radiating element 13A and the feeder line 14 are configured to have a line-symmetrical shape with the central axis of the feeder line 14 as a symmetric line in a plan view.

The radiating element 13B included in the microstrip antenna 10B is obtained by further providing inner frames 132B1, 132B2, 132B3 based on the radiating element 13 (see FIG. 3B). The inner frames 132B1, 132B2, 132B3 are band-shaped conductors whose one end is connected to the portion of the outer frame 131B along the side C1 and the other end is open. The inner frames 132B1, 132B2, 132B3 are extended in a direction parallel to the sides C2 and C3, and the other end reaches the side C4. The inner frames 132B1, 132B2, 132B3 are formed of a solid pattern conductor layer, similarly to the outer frame 131B corresponding to the outer frame 131. In the microstrip antenna 10B, the inner frame 132B2 is arranged on the extension line of the feeder line 14, the inner frame 132B1 is arranged between the side C2 and the inner frame 132B2, and the inner frame 132B3 is the inner frame. It is arranged between 132B2 and side C3. Therefore, the radiating element 13B and the feeder line 14 are configured to have a line-symmetrical shape with the central axis of the feeder line 14 as a symmetric line in a plan view.

As described above, the inner frames 132A, 132B1 to 132B3 formed of the solid pattern conductor film have the capacitance generated between them and the ground conductor 12 as compared with the main part formed of the mesh pattern conductor film. The capacity can be easily increased. Therefore, according to the microstrip antennas 10A and 10B, the capacitance generated between the radiating elements 13A and 13B and the ground conductor 12 by appropriately adjusting the number, width and length of the inner frames 132A and 132B1 to 132B3. Can be set to a desired value or approached to a desired value.

As with the outer frames 131A, 131B and the feeder line 14, each of the inner frames 132A, 132B1, 132B2, and 132B3 is a conductor in which a plurality of fine openings are formed in a matrix instead of the solid pattern conductor layer. The layer may be composed of a conductor layer having an electric resistance equivalent to that of a solid pattern conductor layer. According to this configuration, the main parts of the radiating elements 13A and 13B, the outer frames 131A and 131B, the inner frames 132A, 132B1, 132B2 and 132B3, and the feeder line 14 can be formed by using the same forming process. ..

(Third modification to fifth modification)
The radiating element 13C included in the microstrip antenna 10C is provided with an outer frame 131C provided along all of the sides C1 to C4, and is provided with a strip-shaped outer frame 131C (FIG. 4A). reference). Therefore, the outer frame 131C is an annular conductor layer provided over the entire circumference of the edge region along the sides C1 to C4. Like the outer frame 131, the outer frame 131C is composed of a solid pattern conductor layer.

According to the microstrip antenna 10C, since the outer frame 131C is provided along all the sides C1 to C4, that is, because the outer frame 131C is provided over the entire circumference of the edge region, the radiating element and In a microstrip antenna using a conductor layer of a mesh pattern as a ground conductor, the radiation characteristics can be further improved.

The radiating element 13D included in the microstrip antenna 10D is obtained by adding an inner frame 132D based on the radiating element 13C. Further, the radiating element 13E included in the microstrip antenna 10E is obtained by adding the inner frames 132E1, 132E2, 132E3 based on the radiating element 13C.

The inner frame 132D in the radiating element 13D corresponds to the inner frame 132A in the radiating element 13A. However, the other end of the inner frame 132D is connected to a portion of the outer frame 131D along the side C4.

The inner frames 132E1, 132E2, 132E3 in the radiating element 13E correspond to the inner frames 132B1, 132B2, 132B3 in the radiating element 13B. However, each of the inner frames 132E1, 132E2, and 132E3 has the other end connected to a portion of the outer frame 131E along the side C4.

In one aspect of the present invention, like the radiating elements 13D and 13E, the annular outer frames 131D and 131E and one or more inner frames 132D and inner frames 132E1, 132E2 and 132E3 can be used in combination.

According to the microstrip antennas 10D and 10E, in a microstrip antenna using a conductor layer of a mesh pattern as a radiation element and a ground conductor, between the radiation elements 13D and 13E and the ground conductor 12 while further improving the radiation characteristics. The resulting capacitance can be set to the desired value or approached the desired value.

As with the outer frames 131D, 131E and the feeder line 14, each of the inner frames 132D, 132E1, 132E2, and 132E3 is a conductor in which a plurality of fine openings are formed in a matrix instead of the solid pattern conductor layer. The layer may be composed of a conductor layer having an electric resistance equivalent to that of a solid pattern conductor layer. According to this configuration, the main parts of the radiating elements 13D, 13E, the outer frames 131D, 131E, the inner frames 132D, 132E1, 132E2, 132E3, and the feeder line 14 can be formed by using the same forming process. ..

(6th modification to 8th modification)
As shown in FIG. 5A, the radiation element 13F included in the microstrip antenna 10F is based on the radiation element 13A, and the feeding line 14 is connected to the portion close to the side C1 (1). Notches 133F and 134F, which are examples of a pair of notches, are formed on both sides of the connection point CP, and (2) the shape of the portion of the outer frame 131F close to the side C1 is changed to the notches 133F and 134F. It is obtained by configuring the outer frame 131F so as to border the main portion along the line.

According to the microstrip antenna 10F, the impedance at the connection point CP can be changed by appropriately adjusting the shapes and sizes of the notches 133F and 134F and changing the position of the connection point CP. Therefore, by appropriately adjusting the shapes and sizes of the notches 133F and 134F, the impedance matching between the feeder line 14 and the radiating element 13F can be improved.

The feeder line 14G included in the microstrip antenna 10G is based on the feeder line 14 having a constant width of the strip-shaped conductor. However, the feeder line 14G is configured to be discretely (that is, stepwise) narrower as its width approaches the connection point CP. Specifically, the feeder line 14G is composed of three sections 14G1, 14G2, 14G3 having different widths. The distance from each of the sections 14G1, 14G2, 14G3 to the connection point CP becomes shorter in the order of the sections 14G1, 14G2, 14G3. Further, the magnitude relation of the width W1 of the section 14G1, the width W2 of the section 14G2, and the width W3 of the section 14G3 is W1> W2> W3.

The feeder line 14H included in the microstrip antenna 10H is based on the feeder line 14 having a constant width of the strip-shaped conductor. However, the feeder line 14H is configured to be discretely (that is, stepwise) narrower as its width approaches the connection point CP. Specifically, the feeder line 14H is composed of two sections 14H1 and 14H2 having different widths. The distance from each of the sections 14H1 and 14H2 to the connection point CP becomes shorter in the order of the sections 14H1 and 14H2. Further, the magnitude relationship between the width W1 of the section 14H1 and the width W2 of the section 14H2 is W1> W2.

According to the microstrip antennas 10G and 10H, by adjusting the widths of the feeder lines 14G and 14H as appropriate, the impedance matching between the feeder line 14G and the radiation element 13D and the feeding line 14H and the radiation element 13E are matched. Impedance matching between them can be improved.

Each of the feeder lines 14G and 14H is configured so that the width becomes discretely narrower as the width approaches the connection point CP. However, each of the feeder lines 14G and 14H may be configured so that the width becomes continuously narrower as the width approaches the connection point CP.

[Second Embodiment]
The microstrip antenna module 1 according to the second embodiment of the present invention will be described with reference to FIG. Each of (a) and (b) of FIG. 6 is a plan view and a cross-sectional view of the microstrip antenna module 1, respectively. The cross-sectional view shown in FIG. 6B is obtained when the cross-sectional view taken along the line AA'shown in FIG. 6A is viewed from the direction of the arrow. Further, in the cross-sectional view shown in FIG. 6B, the dimensions of the microstrip antenna 10H in the thickness direction are exaggerated.

As shown in FIGS. 6A and 6B, the microstrip antenna module 1 includes a microstrip antenna 10H, a connector 50, and a solder 60. The microstrip antenna 10H of the present embodiment is based on the microstrip antenna 10H shown in FIG. 5 (c), and has a through hole at the end of the section 14H1 of the feeder line 14H as shown in FIG. 6 (b). It was formed. Therefore, here, the description of the microstrip antenna 10H will be omitted, and the connector 50 and the solder 60 will be described.

The connector 50 is a millimeter-wave coaxial connector, which is one aspect of a two-conductor line. As shown in FIG. 6B, the connector 50 includes an inner conductor 51, an insulating member 52, an outer conductor 53, and a seat plate 54.

The connector 50 is fixed to the main surface 11b of the substrate 11 via the seat plate 54. In the present embodiment, the seat plate 54 is fixed to the main surface 11b by using screws. However, the fixing means for fixing the main surface 11b and the seat plate 54 is not limited to screws, and may be, for example, an adhesive. In FIG. 6, the fixing means is not shown.

The inner conductor 51 protruding from the seat plate 54 reaches the side of the main surface 11a from the side of the main surface 11b through the through hole formed at the end of the section 14H1. The tip of the inner conductor 51 is fixed to the end of the section 14H1 by the solder 60.

In the present embodiment, the connector 50 is an L-shaped connector in which a two-conductor line composed of an inner conductor 51 and an outer conductor 53 is bent at a substantially right angle. However, in the connector 50, the shape of the two-conductor line is not limited.

Further, in FIG. 6, the end portion of the connector 50 on the opposite side to the seat plate 54 (that is, the end portion on the side where the coaxial cable is connected) is not shown. In the connector 50, the shape or standard of the end portion on the side connecting the coaxial cable can be appropriately selected so as to conform to the shape or standard of the connector provided at the end portion of the coaxial cable.

The microstrip antenna module 1 configured in this way can electromagnetically couple the mode in the coaxial cable and the mode in the microstrip antenna 10H via the connector 50.

[Reference Examples and Examples]
A microstrip antenna which is a first reference example to a third reference example of the present invention, a microstrip antenna which is a first embodiment to a third embodiment of the present invention, and a microstrip which is a first comparative example. The antenna 110 will be described with reference to FIGS. 7 to 9. FIG. 7A is a graph showing S-parameters of the microstrip antenna and the microstrip antenna 110 (see FIG. 7B), which are the first reference examples. FIG. 7B is a plan view of the microstrip antenna 110. FIG. 8 is a graph showing the S-parameters of the microstrip antennas of the first reference example to the third reference example. FIG. 9 is a graph showing the S-parameters of the microstrip antenna 10 according to the first to third embodiments.

<Structure of the first comparative example>
First, the microstrip antenna 110, which is the first comparative example, will be described with reference to FIG. 7 (b). The microstrip antenna 110 was obtained by performing the following modifications based on the configuration of the microstrip antenna 10 shown in FIG. The substrate 111, the ground conductor 112 (not shown in FIG. 7B), the radiating element 113, and the feeder line 114 included in the microstrip antenna 110 are each provided by the microstrip antenna 10. It can be compared with the substrate 11, the ground conductor 12, the radiating element 13, and the feeder line 14.

(1) The outer frame 131 of the radiating element 13 included in the microstrip antenna 10 is deleted. That is, the radiating element 113 is composed of a main part composed of a conductor layer of a mesh pattern. The sheet resistance of this mesh pattern is 1Ω / sq.

(2) As the ground conductor 112, a copper foil, which is a solid pattern conductor layer, was used instead of the mesh pattern conductor layer.

As the dielectric material constituting the substrate 111, an acrylic resin having a relative permittivity of 2.23 and a dielectric loss tangent of 0.0003 was used. The thickness of the substrate 111 was set to 2 mm. Further, the main part of the radiating element 113 and the feeding line 114 are formed by separate conductors, and the radiating element 113 is formed by electrically connecting them.

<Structure of 1st Reference Example to 3rd Reference Example and 1st Example to 3rd Example>
Each of the first reference example to the third reference example and the first embodiment to the third embodiment uses a solid pattern conductor layer with respect to the radiating element 113 based on the microstrip antenna 110. By adding the strip-shaped conductor pattern, the microstrip antenna 10 shown in FIG. 1, the microstrip antennas 10A and 10B shown in FIGS. 3A and 3B, and the microstrip antennas 10A to 10B shown in FIGS. It imitates the shape of each radiating element provided in each of the microstrip antennas 10C, 10D, and 10E shown in. That is, in each radiating element, each of the main part, the outer frame, the inner frame, and the feeding line is formed by a separate conductor, and each radiating element is formed by electrically connecting them. There is.

In the first reference example to the third reference example, a copper foil, which is a solid pattern conductor layer, was used as the ground conductor 12 instead of the mesh pattern conductor layer. In the first to third embodiments, a conductor layer having a mesh pattern was used as the ground conductor 12.

The shapes of the respective radiating elements of the first reference example to the third reference example and the first embodiment to the third embodiment are as follows. The width of the added strip-shaped conductor pattern is 0.4 mm.

The radiating element provided in the first reference example has the same shape as the radiating element 13D shown in FIG. 4B. The radiating element provided in the second reference example has the same shape as the radiating element 13C shown in FIG. 4A. The radiating element provided in the third reference example has the same shape as the radiating element 13E shown in FIG. 4 (c). The radiating element provided in the first embodiment has the same shape as the radiating element 13 shown in FIG. The radiating element provided in the second embodiment has the same shape as the radiating element 13A shown in FIG. 3A. The radiating element provided in the third embodiment has the same shape as the radiating element 13D shown in FIG. 3B.

The effect of the microstrip antenna according to one aspect of the present invention was verified by using the first reference example to the third reference example and the first embodiment to the third embodiment configured as described above.

<Radiation characteristics>
In FIG. 7A, S-parameters S11 and S12 of the first reference example and S-parameters S11 and S12 of the first comparative example are plotted. Comparing the S-parameter S12 of the first reference example and the S-parameter S12 of the first comparative example, the S-parameter S12 of the first reference example significantly exceeds the S-parameter S12 of the first comparative example. It turned out that. That is, it was found that the first reference example had improved radiation characteristics as compared with the first comparative example. This is a band-shaped conductor pattern corresponding to each of the annular outer frame 131D and one inner frame 132D, as in the radiation element 13D of the microstrip antenna 10D shown in FIG. 4B, as the first reference. This is probably because the microstrip antenna in the example is equipped.

FIG. 8 shows S-parameters S11 and S12 of the first reference example, S-parameters S11 and S12 of the second reference example, and S-parameters S11 and S12 of the third reference example. The S-parameters S11 and S12 of the first reference example shown in FIG. 8 are the same as the S-parameters S11 and S12 of the first reference example shown in FIG. 7 (a). With reference to FIG. 8, it was found that each of the first reference example to the third reference example showed almost the same radiation characteristics in the S parameter S12, although some differences were observed in the S parameter S11. .. Therefore, it was found that each of the second reference example and the third reference example, like the first reference example, had improved radiation characteristics as compared with the first comparative example.

FIG. 9 shows S-parameters S11 and S12 of the fourth reference example, S-parameters S11 and S12 of the fifth reference example, and S-parameters S11 and S12 of the sixth reference example. With reference to FIG. 9, by changing the number of inner frames to 0 (fourth reference example), one (fifth reference example), and three (sixth reference example), the operating band can be changed. It was found that the center frequency shifts to the high frequency side. Further, it was found that the S-parameter S12 of the fourth reference example to the sixth reference example exceeds 0 dBi in a band of at least 3.5 GHz or more and 3.9 GHz or less. Therefore, it was found that each of the fourth reference example to the sixth reference example had improved radiation characteristics as compared with the first comparative example. Further, also in the first reference example to the third reference example, the microstrip antenna having a band of 3.5 GHz or more and 3.7 GHz or less exceeds 0 dBi and has an operating band of 3.5 GHz band has good performance. Was confirmed.

[Further embodiments, etc.]
<9th variant>
The microstrip antenna 10I, which is a ninth modification of the microstrip antenna 10, will be described with reference to FIG. FIG. 10A is a cross-sectional view of a part of the microstrip antenna 10I. In FIG. 10A, a cross section of a main part of the radiating element 13 of the microstrip antenna 10I is shown. FIG. 10B is an enlarged cross-sectional view of a part of the microstrip antenna 10I, which is an enlarged cross-sectional view of the vicinity of the radiating element 13 and the vicinity of the ground conductor 12. In addition, in (a) and (b) of FIG. 10, it is not shown that the ground conductor 12 and the radiating element 13 are composed of the conductor layer of the mesh pattern.

As shown in FIG. 1, in the microstrip antenna 10, the radiation element 13 and the feeder line 14 are directly formed on the main surface 11a of the substrate 11, and the ground conductor 12 is directly formed on the main surface 11b of the substrate 11. Has been done.

On the other hand, as shown in FIG. 10A, the microstrip antenna 10I includes the substrate 11, the ground conductor 12, the radiating element 13, and the feeder line 14 (not shown), as well as the adhesive layers 15 and 16. , The dielectric layers 17 and 18 are further provided.

The adhesive layer 15 is an example of the second fixing member, and fixes the dielectric layer 17 described later on the main surface 11b.

The adhesive layer 16 is an example of the first fixing member, and fixes the dielectric layer 18 described later on the main surface 11a.

It is preferable that the adhesive layers 15 and 16 have a uniform thickness and are configured so that the dielectric layers 17 and 18 are less likely to be distorted when the dielectric layers 17 and 18 described later are fixed. In the present embodiment, the adhesive layers 15 and 16 are adhesive sheets made of a translucent material, and an adhesive sheet called OCA (Optical Clear Adhesive) is used. However, the adhesive layers 15 and 16 are not limited to OCA, and a suitable adhesive can be selected from commercially available adhesive sheets and adhesives.

The dielectric layer 17 is an example of the second dielectric layer, and as shown in FIG. 10 (b), the first laminated layer 171 and the second laminated layer 172, which are a pair of light-transmitting laminated layers, It is composed of. The first laminated layer 171 and the second laminated layer 172 sandwich the ground conductor 12, that is, they are laminated.

The dielectric layer 18 is an example of the first dielectric layer, and as shown in FIG. 10 (b), the first laminate layer 181 and the second laminate layer 182, which are a pair of light-transmitting laminate layers, It is composed of. The first laminating layer 181 and the second laminating layer 182 sandwich the radiating element 13, that is, they are laminated. Although not shown in FIG. 10, the feeder line 14 is also sandwiched by the first laminated layer 181 and the second laminated layer 182, similarly to the radiating element 13.

The first laminated layer 171 and the second laminated layer 172, the first laminated layer 181 and the second laminated layer 182 constituting the dielectric layers 17 and 18 have a uniform thickness, and the ground conductor 12 and the radiating element to be sandwiched therewith are uniform in thickness. It is preferable that the 13 and the feeding line 14 are configured so that distortion is unlikely to occur. In the present embodiment, an ultraviolet curable resin is used as the first laminate layer 171, the second laminate layer 172, the first laminate layer 181 and the second laminate layer 182. However, the first laminate layer 171 and the second laminate layer 172, the first laminate layer 181 and the second laminate layer 182 are not limited to these, and are appropriately selected from among the translucent resin materials. be able to.

Further, in the present embodiment, the dielectric layer 17 includes a pair of laminated layers 171 and 172, each of which holds the ground conductor 12 by sandwiching the ground conductor 12. Similarly, the dielectric layer 18 includes a pair of laminated layers 181, 182, each of which holds the radiating element 13 and the feeder line 14 by sandwiching them. However, each of the dielectric layers 17 and 18 may be composed of a single laminated layer. In this case, one surface of the ground conductor 12, the radiating element 13, and the feeder line 14 is not covered by the laminate layer and is exposed, but the exposed side is fixed so as to be close to the adhesive layers 15 and 16. It is preferable to do so. By fixing in this way, the ground conductor 12, the radiating element 13, and the feeder line 14 can be protected by the dielectric layers 17 and 18.

According to the microstrip antenna 10I, each of the radiation element 13 and the feeder line 14 held by the dielectric layer 18 and the ground conductor 12 held by the dielectric layer 17 are manufactured separately from the substrate 11. The microstrip antenna 10I is formed by fixing the dielectric layer 18 (181) to the main surface 11a using the adhesive layer 16 and fixing the dielectric layer 17 (172) to the main surface 11b using the adhesive layer 15. Can be manufactured. Therefore, since the radiating element 13, the feeder line 14, and the ground conductor 12 can be manufactured independently of the substrate 11, the degree of freedom in manufacturing the microstrip antenna can be increased. By extension, the microstrip antenna 10I can be easily manufactured as compared with the microstrip antenna 10 shown in FIG.

<Third embodiment>
The microstrip antenna unit 2 according to the third embodiment of the present invention will be described with reference to FIGS. 11 and 12. FIG. 11 is a plan view of the microstrip antenna unit 2. FIG. 12 is a side view of the microstrip antenna unit 2 installed on the surface of the window glass 100.

(Window glass)
The window glass 100 is an example of another structure. As shown in FIG. 12, the window glass 100 includes a plate-shaped member 101 and a grid 102.

The plate-shaped member 101 is made of glass. In the present embodiment, the thickness of the plate-shaped member 101 is 5 mm. However, the thickness of the plate-shaped member 101 is not limited to this and can be appropriately determined.

The lattice 102 is formed by crossing a plurality of copper wires in a lattice pattern. The grid 102 is embedded inside the 101. In this embodiment, 20 mm is adopted as the pitch in the grid pattern of the grid 102. The lattice 102 suppresses the scattering of fragments of the plate-shaped member 101 when the plate-shaped member 101 is broken. The wire constituting the lattice 102 is not limited to copper, and may be made of another metal. The pitch in the lattice 102 is not limited to 20 mm, and can be appropriately adjusted.

(Microstrip antenna unit)
As shown in FIG. 11, the microstrip antenna unit 2 includes four microstrip antennas 20C1 to 20C4 and spacers 291 to 294. The microstrip antennas 20C1 to 20C4 are examples of the first to fourth microstrip antennas.

In the microstrip antenna unit 2, the substrates 21 constituting the four microstrip antennas 20C1 to 20C4 are a single substrate. That is, the substrate 21 is shared between the microstrip antennas 20C1 to 20C4. The substrate 21 is configured in the same manner as the substrate 11 except for the size when viewed in a plan view.

A radiation element group 23 and a feeder group 24 are arranged on the main surface 21a, which is one of the main surfaces of the substrate 21. A ground conductor 22 is arranged on the main surface 21b, which is the other main surface of the substrate 21. As in the case of the ninth modification shown in FIG. 10, the radiation element group 23 and the feeder line group 24 are laminated by the dielectric layer 28 corresponding to the dielectric layer 18, and the ground conductor 22 is , Laminated by the dielectric layer 27 corresponding to the dielectric layer 17. In FIG. 11, the dielectric layer 28 is not shown.

Each of the microstrip antennas 20C1 to 20C4 is configured in the same manner as the microstrip antenna 10C shown in FIG. 4 (a). That is, in each of the microstrip antennas 20C1 to 20C4, (1) each of the radiation elements 23C1 to 23C4 corresponds to the radiation element 13C of the microstrip antenna 10C, and (2) supplies a part of the feeder line group 24. Each of the electric wires 2411 to 2414 corresponds to the feeder line 14 of the microstrip antenna 10C, and (3) each of the connection points CP1 to CP4 corresponds to the connection point CP of the microstrip antenna 10C. Therefore, in the present embodiment, detailed description of the radiation element group 23 and the feeder lines 2411 to 2414 of the microstrip antenna unit 2 will be omitted.

In each of the microstrip antennas 20C1 to 20C4, the long sides of the radiating elements 23C1 to 23C4 are parallel to the x-axis direction, and the short sides of the radiating elements 23C1 to 23C4 are parallel to the y-axis direction. It is arranged at a position corresponding to each vertex of the rectangular shape. In the present embodiment, the direction from the microstrip antennas 20C3 and 20C4 to the microstrip antennas 20C1 and 20C2 is defined as the y-axis positive direction, and each of the x-axis, y-axis, and z-axis forms a right-handed Cartesian coordinate system. Each direction of the x-axis and the z-axis is defined so as to be performed. Further, the Cartesian coordinate system is defined so that the origin is located at a position corresponding to the midpoint between the branch portion B1 and the branch portion B2, which will be described later.

In the present embodiment, each of the feeder lines 2411 and 2413 is drawn out from each of the connection points CP1 and CP3 in the negative direction on the y-axis, then bent by 90 ° and extended in the positive direction on the x-axis. In the present embodiment, each of the feeder lines 2412 and 2414 is drawn out from each of the connection points CP2 and CP4 in the negative direction on the y-axis, then bent by 90 ° and extended in the negative direction on the x-axis.

The feeder line group 24 of the microstrip antenna unit 2 is composed of the feeder lines 2411 to 2414 of the microstrip antennas 20C1 to 20C4, the auxiliary feeder lines 2421 and 2422, and the main feeder line 243.

In the microstrip antenna unit 2, each of the feeder lines 2411 to 2414 is configured to have the same length. The end of the feeder line 2411 on the opposite side of the connection point CP1 and the end of the feeder line 2412 on the opposite side of the connection point CP2 are connected. The end of the feeder line 2413 on the opposite side of the connection point CP3 and the end of the feeder line 2414 on the opposite side of the connection point CP4 are connected.

The sub-feed line 2421 and 2422 and the main feeder line 243 are strip-shaped conductor layers like the feeder lines 2411 to 2414 corresponding to the feeder line 14.

Each of the auxiliary feeder lines 2421 and 2422 is formed in a straight line. In this embodiment, the lengths of the auxiliary feeders 2421 and 2422 are equal. However, as will be described later, the lengths of the auxiliary feeders 2421 and 2422 may be different.

One end of the auxiliary feeder line 2421 is connected to an end portion of the feeder line 2411 opposite to the connection point CP1 and an end portion of the feeder line 2412 opposite to the connection point CP2. One end of the auxiliary feeder line 2422 is connected to an end portion of the feeder line 2413 opposite to the connection point CP3 and an end portion of the feeder line 2414 opposite to the connection point CP4. The subfeed line 2421 extends from one end to the other end in the negative y-axis direction, and the subfeed line 2422 extends from one end to the other end in the y-axis. It is stretched in the positive direction. The other end of the subfeed line 2421 and the other end of the subfeed line 2422 are connected.

The main feeder line 243 is configured by connecting the first portion 2431, the second portion 2432, the third portion 2433, and the fourth portion 2434 in this order. The first portion 2431 constitutes one end and the fourth portion 2434 constitutes the other end. Further, the second portion 2432 and the third portion 2433 form an intermediate portion.

The first portion 2431 has a portion stretched in the positive direction of the x-axis and a portion bent by 90 ° and stretched in the positive direction of the y-axis. The second portion 2432 has a portion that is stretched in the positive direction of the y-axis and a portion that is bent 90 ° and stretched in the positive direction of the x-axis. The third portion 2433 and the fourth portion 2434 are extended in the positive direction on the x-axis. As described above, the main feeder line 243 is formed in a crank shape by being bent by 90 ° in two extending directions. One end of the first portion 2431 is connected to the other end of the subfeed line 2421 and the other end of the subfeed line 2422.

In the following, the portion where the feeder lines 2411 and 2412 and the sub-feed line 2421 are connected is referred to as a branch portion B1, and the portion where the feeder lines 2413 and 2414 and the sub-feed line 2422 are connected is referred to as a branch portion B2. .. Further, the portion where the sub-feed line 2421 and 2422 and the main feeder line 243 are connected is referred to as a branch portion B3. Each of the branch portions B1, B2, and B3 is an example of the first branch portion, the second branch portion, and the third branch portion, respectively. The branch B1 bundles the feeders 2411 and 2412 into the sub-feed line 2421, the branch B2 bundles the feeders 2413 and 2414 into the sub-feed line 2422, and the branch B3 mainly supplies the sub-feed lines 2421 and 2422. Collect in electric wire 243.

In the present embodiment, since the lengths of the sub-feed line 2421 and the sub-feed line 2422 are the same, the distance from the branch portion B3 to the branch portion B1 and the distance from the branch portion B3 to the branch portion B2 Are equal. That is, the branch portion B3 is located at the origin of the Cartesian coordinate system, which is the midpoint between the branch portion B1 and the branch portion B2. Hereinafter, the position of the branch portion B3 along the y-axis direction is referred to as a position y3. In this embodiment, y3 = 0 mm.

Therefore, in the present embodiment, the distance from the branch portion B3 to the connection point CP1, the distance from the branch portion B3 to the connection point CP2, the distance from the branch portion B3 to the connection point CP3, and the distance from the branch portion B3 to the connection point CP4. The distances are equal, that is, the feeding line group 24 is configured to be an equal length wiring having the same length to each of the connection points CP1 to CP4.

Spacers 291 to 294 are columnar rod-shaped members. The height h (length) of each of the spacers 291 to 294 is equal. In each of the spacers 291 to 294, one end is fixed to the main surface 21b of the substrate 21 via the dielectric layer 27, and the other end is fixed to one main surface of the window glass 100. ing. Therefore, the spacers 291 to 294 are provided on the main surface 21b side of the substrate 21, and form a predetermined distance equal to the height h between the substrate 21 and the window glass 100.

In this embodiment, the height h is 85.4 mm. 85.4 mm corresponds to the execution wavelength λe of an electromagnetic wave having a frequency of 3.51 GHz. This electromagnetic wave is included in the 3.5 GHz band, which is the operating band of the microstrip antenna unit 2. However, the height h is not limited to 85.4 mm, and should be appropriately set according to whether or not the window glass 100 includes the grid 102 and the composition of the glass constituting the plate-shaped member 101. Can be done.

In this embodiment, of the intervals between the radiating elements 23C1 to 23C4, 1/2 of the execution wavelength λe described above is adopted as the pitch ΔGa in the y-axis direction.

(Effect of microstrip antenna unit)
As described above, in the microstrip antenna unit 2, the radiation element group 23 and the feeder line group 24 are laminated by the dielectric layer 28, and the ground conductor 22 is laminated by the dielectric layer 27.

According to this configuration, the degree of freedom in manufacturing the microstrip antenna can be increased as in the case of the microstrip antenna 10I shown in FIG.

Further, in the microstrip antenna unit 2, the substrates 21 constituting the four microstrip antennas 20C1 to 20C4 are a single substrate.

According to this configuration, for example, the radiation characteristics can be further improved as compared with the case where the radiation element 23C1 of the microstrip antenna 20C1 is excited independently. Further, since each of the microstrip antennas 20C1 to 20C4 is configured by using the substrate 21 which is a single substrate, it becomes easy to align the directivity of each of the microstrip antennas 20C1 to 20C4, or it becomes easy to control. Become.

Further, the feeder line group 24 is configured to be an equal length wiring having the same length from the branch portion B3 to each of the connection points CP1 to CP4.

According to this configuration, since each of the radiating elements 23C1 to 23C4 is excited in the same phase, the gain of the microstrip antenna unit 2 can be increased as compared with the case where y3 = 0 mm. According to this configuration, the gain of the microstrip antenna unit 2 becomes maximum in the direction along the z-axis.

Further, in the feeder line group 24, it is possible to adopt a configuration in which the distance from the branch portion B3 to the branch portion B1 and the distance from the branch portion B3 to the branch portion B2 are different. That is, a value other than 0 mm can be adopted as the position y3. In this case, the feeder line group 24 has the same length from the branch portion B3 to each of the connection points CP1 and CP2, and the same length from the branch portion B3 to each of the connection points CP3 and CP4, but these 2 The lengths of the two are different.

According to this configuration, the radiating elements 23C1, 23C2 and the radiating elements 23C3, 23C4 are excited in different phases. As a result, the direction in which the gain of the microstrip antenna unit 2 is maximized can be tilted in the yz plane from the direction along the z-axis. Therefore, when designing the microstrip antenna unit 2, by changing the position y3, the direction in which the gain is maximized can be changed without changing the basic structure of the microstrip antenna unit 2.

Further, the microstrip antenna unit 2 includes spacers 291 to 294.

According to this configuration, when the microstrip antenna unit 2 is installed on the surface of the window glass 100, the microstrip antenna unit 2 can be separated from the window glass 100 by a predetermined distance corresponding to the height h. By appropriately designing a predetermined distance, it is possible to reduce the influence of the window glass 100 on the microstrip antenna unit 2 even when a conductor such as a metal such as a grid 102 is present inside the window glass 100. Can be done. Therefore, it is possible to suppress a decrease in the radiation characteristics of the microstrip antenna unit 2.

For example, as shown in FIG. 12, when the window glass 100 includes the grid 102, the height h preferably exceeds 1/4 of the execution wavelength λe of the electromagnetic wave included in the operating band. Further, for example, when the window glass 100 does not include the lattice 102, that is, when it is composed of only the plate-shaped member 101, the height h is other than 1/4 of the execution wavelength λe of the electromagnetic wave included in the operating band. Is preferable. According to these configurations, even when the microstrip antenna unit 2 is installed near the surface of the window glass 100, it is possible to suppress a decrease in radiation characteristics.

<Fourth Embodiment>
The microstrip antenna unit group 3 according to the fourth embodiment of the present invention will be described with reference to FIG. FIG. 13 is a plan view of the microstrip antenna unit group 3.

As shown in FIG. 13, the microstrip antenna unit group 3 includes four microstrip antenna units 2A to 2D. Each of the microstrip antenna units 2A to 2D is configured in the same manner as the microstrip antenna unit 2 shown in FIGS. 11 and 12. In the present embodiment, the four microstrip antenna units 2 are distinguished by adding the reference numerals "A" to "D" after the reference numeral "2".

However, the number of microstrip antenna units constituting the microstrip antenna unit group 3 is not limited to four, and can be appropriately designed.

In the microstrip antenna unit group 3, a single substrate (the substrate 21 shown in FIGS. 11 and 12) constituting each of the microstrip antenna units 2A to 2D is shared between the microstrip antenna units 2A to 2D. Has been done. In the present embodiment, the single substrate shared between the microstrip antenna units 2A to 2D is referred to as a substrate 31. The substrate 31 is configured in the same manner as the substrate 21 shown in FIG. 11, except for the size when viewed in a plan view.

Further, the microstrip antenna unit group 3 includes spacers 291 to 294 like the microstrip antenna unit 2.

On the main surface 31a, which is one of the main surfaces of the substrate 31, the radiating element group 23A, the feeding line group 24A, the radiating element group 23B, the feeding line group 24B, the radiating element group 23C, the feeding line group 24C, the radiating element group 23D, And the feeder line group 24D are arranged in a state of being laminated on the dielectric layer (corresponding to the dielectric layer 28). Further, on the other main surface of the substrate 31 (not shown in FIG. 13), the ground conductor corresponding to the ground conductor 22 is arranged in a state of being laminated on the dielectric layer (corresponding to the dielectric layer 27). .. In these respects, the microstrip antenna unit group 3 is similar to the microstrip antenna unit 2 shown in FIG. Note that in FIG. 13, the illustration of the dielectric layer corresponding to the dielectric layer 28 is omitted.

The Cartesian coordinate system shown in FIG. 13 is defined in the same manner as the Cartesian coordinate system shown in FIG.

Each of the microstrip antenna units 2A to 2D is arranged in a row along the y-axis direction. However, each of the microstrip antenna units 2A to 2D may be arranged in a plurality of rows. In particular, when the number of microstrip antenna units constituting the microstrip antenna unit group 3 is large, it is preferable to arrange each of the microstrip antenna units in a matrix.

Further, each of the microstrip antenna units 2A to 2D is arranged so that the pitch ΔGu between adjacent microstrip antenna units (for example, the microstrip antenna units 2A and 2B) is equal. In this embodiment, 85.4 mm is adopted as the pitch ΔGu. 85.4 mm corresponds to the execution wavelength λe of an electromagnetic wave having a frequency of 3.51 GHz. This electromagnetic wave is included in the 3.5 GHz band, which is the operating band of the microstrip antenna unit group 3. However, the pitch ΔGu is not limited to 85.4 mm. The pitch ΔGu may be appropriately designed according to, for example, the number of radiating elements (4 in FIG. 13) provided in each of the microstrip antenna units 2A to 2D, the arrangement method, and the like.

As described above, in the microstrip antenna unit group 3, the substrate 31 may be shared between the microstrip antenna units 2A to 2D. That is, a plurality of microstrip antenna units may be integrated on a single substrate 31.

Further, in the microstrip antenna unit group 3, each of the microstrip antenna units 2A to 2D can adopt a different value of the position y3.

According to this configuration, although each of them shares a single substrate 31, the direction in which the gain in each of the microstrip antenna units 2A to 2D is maximized can be changed. Therefore, for example, when the microstrip antenna unit group 3 is installed on the window glass of a building, the positions y3 are different from each other as compared with the case where the same value of the position y3 is adopted in all the microstrip antenna units 2A to 2D. The microstrip antenna unit group 3 adopting the value of can cover a wider range.

<Fourth Example>
A microstrip antenna 10C (see (a) of FIG. 4), which is a fourth embodiment of the present invention, and a microstrip antenna, which is a second comparative example, will be described with reference to FIG. Each of FIGS. 14A and 14B is a graph showing the S-parameter S11 and the gain of the microstrip antenna 10C of the fourth embodiment and the second comparative example, respectively.

The second comparative example is based on the microstrip antenna 10C, by replacing the main parts of the ground conductor 12 and the radiating element 13C provided in the microstrip antenna 10C from the conductor layer of the mesh pattern to the conductor layer of the solid pattern. can get.

In each of the following embodiments, the band in which the S parameter S11 is −10 dB or less is determined to be the operating band.

In the second comparative example, as shown in FIG. 14A, the operating bandwidth was 100 MHz and the maximum gain was 7.11 dBi.

On the other hand, the microstrip antenna 10C of the fourth embodiment had an operating bandwidth of 225 MHz and a maximum gain of 2.9 dBi.

As described above, the microstrip antenna 10C of the fourth embodiment is less noticeable even when attached to the window glass, and the bandwidth of the operating band is made larger than that of the second comparative example. It was possible to widen the bandwidth.

<Fifth Example>
The microstrip antenna unit 2 (see FIGS. 11 and 12), which is a fifth embodiment of the present invention, and the microstrip antenna unit, which is a third comparative example, will be described with reference to FIG. Each of FIGS. 15A and 15B is a graph showing the S-parameter S11 and the gain of the microstrip antenna unit 2 of the fifth embodiment and the third comparative example, respectively.

In the third comparative example, the microstrip antenna unit 2 is used as a base, and the main parts of the ground conductors 22 included in the microstrip antennas 20C1 to 20C4 and the radiating elements 23C1 to C4 constituting the radiating element group 23 are conductors having a mesh pattern. It is obtained by replacing the layer with a solid pattern conductor layer.

Further, in the fifth embodiment, 0.1 mm was adopted as the width of the outer frame 131C (see (a) of FIG. 4) of the radiating elements 23C1 to 23C4, and 0 mm was adopted as the position y3 (see FIG. 11). .. Further, in the fifth embodiment, the fifth embodiment group and the sixth embodiment group described later, the radiation characteristics of the microstrip antenna unit 2 alone are not considered in consideration of the window glass 100 shown in FIG. I simulated it.

In the third comparative example, as shown in FIG. 15A, the operating bandwidth was 110 MHz and the maximum gain was 12.9 dBi.

On the other hand, the microstrip antenna unit 2 had an operating bandwidth of 510 MHz and a maximum gain of 9.5 dBi.

As described above, the microstrip antenna unit 2 can be made inconspicuous even when attached to the window glass, and the bandwidth of the operating band can be made wider than that of the third comparative example. It was. In addition, although the gain was inferior to that of the third comparative example, it showed a good value approaching 10 dBi in a wide band. Further, when the microstrip antenna 10C of the fourth embodiment and the microstrip antenna unit 2 of the fifth embodiment are compared, the microstrip antenna unit 2 can improve both the S parameter S11 and the gain. Do you get it.

<Fifth Example Group>
The microstrip antenna unit 2 (see FIGS. 11 and 12), which is the fifth embodiment group of the present invention, will be described with reference to FIG. Each of (a) and (b) of FIG. 16 is a graph showing the S-parameter S11 and the gain of the microstrip antenna unit 2 which is the fifth embodiment group, respectively.

The microstrip antenna unit 2 of the fifth embodiment is based on the microstrip antenna unit 2 of the fifth embodiment, and the width of the outer frame 131C (see (a) of FIG. 4) is set to 0 mm, 0 mm. It is obtained by varying to 05 mm, 0.1 mm, 0.2 mm, and 0.5 mm. In other words, among the microstrip antenna units 2 shown in FIG. 16, the microstrip antenna unit 2 having an outer frame 131C having a width of 0.1 mm is a fifth embodiment.

With reference to FIGS. 16A and 16B, it was found that the wider the width of the outer frame 131C than 0.05 mm, the better the S-parameter S11 and the gain.

<Sixth Example Group>
The microstrip antenna unit 2 (see FIGS. 11 and 12), which is the sixth embodiment group of the present invention, will be described with reference to FIG. FIG. 17 is a graph showing the gain of the microstrip antenna unit 2 which is the sixth embodiment group. The angle shown in FIG. 17 is the angle formed by the positive z-axis direction and the direction in which the gain is maximized in the yz plane shown in FIG.

The microstrip antenna unit 2 of the sixth embodiment is based on the microstrip antenna unit 2 of the fifth embodiment, and the positions y3 are set to -9 mm, -7 mm, -5 mm, 5 mm, 7 mm, and 9 mm. Obtained by changing. Although not shown in FIG. 17, when y3 = 0 mm (that is, in the case of the microstrip antenna unit 2 of the fifth embodiment), the gain is maximum at an angle of 0 °, and the value is 9.5 dBi. there were.

With reference to FIG. 17, when the value of the position y3 is changed within the range of -9 mm or more and 9 mm or less, the angle at which the gain is maximized may change within the range of about -15 ° or more and 15 ° or less. Do you get it. That is, it was found that the directivity of the microstrip antenna unit 2 can be adjusted by adjusting the value of the position y3.

<7th Example Group and 8th Example Group>
The microstrip antenna unit 2 (see FIGS. 11 and 12), which is the seventh embodiment group and the eighth embodiment group of the present invention, will be described with reference to FIGS. 18 and 19. Each of FIGS. 18A and 18B is a graph showing the S-parameter S11 and the gain of the microstrip antenna unit 2 of the seventh embodiment group, respectively. Each of FIGS. 19A and 19B is a graph showing the S-parameter S11 and the gain of the microstrip antenna unit 2 of the eighth embodiment group, respectively.

In the seventh example group, as shown in FIG. 12, the radiation characteristics of the microstrip antenna unit 2 installed near the surface of the window glass 100 were simulated via the spacers 291 to 294. In the seventh embodiment, a window glass 100 (a window glass 100 composed of only the plate-shaped member 101) without the grid 102 was assumed when the simulation was performed.

The seventh example group is obtained by changing the height h of the spacers 291 to 294 to 5 mm, 10 mm, 21.35 mm, 42.7 mm, and 85.4 mm.

In the eighth example group, similarly to the seventh example group, the radiation characteristics of the microstrip antenna unit 2 installed near the surface of the window glass 100 were simulated via the spacers 291 to 294. In the eighth example group, a window glass 100 provided with a plate-shaped member 101 and a grid 102 was assumed when simulating. In addition, 20 mm was adopted as the pitch of the lattice 102.

The eighth example group is obtained by changing the height h of the spacers 291 to 294 to 10 mm, 21.35 mm, 42.7 mm, and 85.4 mm.

85.4 mm corresponds to the execution wavelength λe of an electromagnetic wave having a frequency of 3.51 GHz. Therefore, each of 42.7 mm and 21.35 mm corresponds to 1/2 and 1/4 of the execution wavelength λe of the electromagnetic wave having a frequency of 3.51 GHz, respectively.

In the 7th example group and the 8th example group, 5 mm was adopted as the thickness of the plate-shaped member 101, and Dk = 2.5 was adopted.

Referring to FIG. 18, the microstrip antenna unit 2 installed near the surface of the window glass 100 composed of only the plate-shaped member 101 has a height h changed within a range of 5 mm or more and 85.4 mm or less. The case was found to show good S-parameters and gain except when h = 21.35 mm. Therefore, in this case, it was found that the height h is preferably set to a value other than 1/4 of the execution wavelength λe of the electromagnetic wave having a predetermined wavelength included in the operating band.

Referring to FIG. 19, the microstrip antenna unit 2 installed near the surface of the window glass 100 composed of the plate-shaped member 101 and the lattice 102 changes the height h within a range of 10 mm or more and 85.4 mm or less. It was found that when the height h was set to 42.7 mm and 85.4 mm, good S-parameters and gains were exhibited. Therefore, in this case, it was found that it is preferable to set the height h to be more than 1/2 of the execution wavelength λe of the electromagnetic wave having a predetermined wavelength included in the operating band.

Although the graph is omitted, in the microstrip antenna unit 2, the wider the grid-like pitch of the grid 102, the weaker the influence of the grid 102, and the narrower the pitch, the stronger the influence of the grid 102. I also found out. Therefore, it is preferable that the height h is appropriately designed in consideration of the pitch value.

[Additional notes]
The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.

1 Microstrip antenna module 2, 2A to 2D Microstrip antenna unit 3 Microstrip antenna unit group 10, 10A to 10I Microstrip antenna 11, 21, 31 Substrate 12, 22 Ground conductor 13, 13A to 13F Radiation element 23, 23A to 23D Radiation element group 23C1-23C4 Radiation element 14, 14G, 14H Feed line 24, 24A to 24D Feed line group 2411 to 2414 Feed line 2421, 2422 Sub-feed line (1st sub-feed line, 2nd sub-feed line)
243 Main feeder B1, B2, B3 branch (1st branch, 2nd branch, 3rd branch)
15, 16 Adhesive layer (second fixing member, first fixing member)
17, 18 Dielectric layers (second dielectric layer, first dielectric layer)
171 and 181 1st laminate layer 172, 182 2nd laminate layer 291-294 Spacer 50 Connector 51 Inner conductor 52 Insulation member 53 Outer conductor 60 Solder

Claims (11)

A transparent dielectric substrate and
A radiating element formed on one of the main surfaces of the substrate, including a main portion composed of a conductor layer having a mesh pattern, and having a rectangular shape when viewed in a plan view.
Of the other main surface of the substrate, a ground conductor formed in a region including at least the radiating element when viewed in a plan view and including a main portion composed of a conductor layer of a mesh pattern.
A feeder line provided on the same surface as the radiating element and having one end connected to the radiating element on a first side which is one side of a rectangle circumscribing the radiating element.
The radiating element has a band-shaped outer frame that borders the radiating element along at least the first side, and is composed of a conductor layer having a lower electrical resistance than the main part of the radiating element. Is provided,
A microstrip antenna that features that. The outer frame borders the radiating element at least along the first side and the second and third sides sandwiching the first side.
The microstrip antenna according to claim 1. The outer frame is a band-shaped outer frame that borders the radiating element along all four sides of the rectangle.
The microstrip antenna according to claim 2. The radiating element is a band-shaped inner frame having one end connected to a portion of the outer frame along the first side and extending in a direction perpendicular to the first side. An inner frame made of a conductor layer having a lower electric resistance than the main part of the above is further provided.
The microstrip antenna according to any one of claims 1 to 3. The width of the feeder becomes narrower as it approaches the connection point to which the feeder is connected among the first sides.
The microstrip antenna according to any one of claims 1 to 4. A pair of notches are formed on both sides of the connection point to which the feeder line is connected in the first side.
The microstrip antenna according to any one of claims 1 to 5, wherein the microstrip antenna. A first dielectric layer that holds the radiating element, a second dielectric layer that holds the ground conductor, and
A first fixing member for fixing at least one of the first dielectric layer and the radiating element to one main surface of the substrate.
The other main surface of the substrate is further provided with a second dielectric layer and a second fixing member for fixing at least one of the ground conductors.
The microstrip antenna according to any one of claims 1 to 6, wherein the microstrip antenna. A microstrip antenna unit including a plurality of microstrip antennas according to any one of claims 1 to 7.
The substrate that makes up each microstrip antenna is a single substrate,
A microstrip antenna unit characterized by that. The plurality of microstrip antennas are composed of first to fourth microstrip antennas, each of which is provided at a position corresponding to each of the rectangular vertices.
A first branch portion that combines the feed lines of the first microstrip antenna and the second microstrip antenna into a first sub-feed line, and
A second branch portion that combines the feeder lines of the third microstrip antenna and the fourth microstrip antenna into a second sub-feed line, and
Further provided with a third branch portion for combining the first sub-feed line and the second sub-feed line into a main feed line.
The distance from the first branch to the radiating element of the first microstrip antenna, the distance from the first branch to the radiating element of the second microstrip antenna, and the distance from the second branch to the third microstrip antenna. The distance to the radiating element of the above and the distance from the second branch to the radiating element of the fourth microstrip antenna are equal and
The distance from the third branch to the first branch and the distance from the third branch to the second branch are different.
The microstrip antenna unit according to claim 8. A spacer provided on one main surface side of the single substrate, further comprising a spacer that provides a predetermined distance between the single substrate and the other structure.
The microstrip antenna unit according to claim 8 or 9. A group of microstrip antenna units including a plurality of microstrip antenna units according to any one of claims 8 to 10.
A single substrate constituting each microstrip antenna unit is shared among the microstrip antenna units.
A group of microstrip antenna units characterized by this.

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