JPH10335924A - Micro-strip antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the gain control of a low elevation angle that includes a back side and the control of a crossed polarization component and to make an antenna light weight and easy to move by having one or plural parasitic devices which consist of conductors that are arranged, surrounding a radiation conductor that is formed on the surface of a dielectric substrate and a ground plate which is fixed and electrically connected to a ground conductor that is formed on a rear plane of the substrate. SOLUTION: In a micro-strip antenna element 11, a circular radiation conductor 12 is formed on the surface of a dielectric, and a ground conductor is formed on a rear plane. Further, it has a ground plate 21 that is fixed and is electrically connected to the ground electrode, a foamed styrene 22 that is fittingly attached to the plate 21 and parasitic devices 13 to 15 which are fixed concentrically with the element 11 and consist of circular plate conductors. It has an equivalent effect to a choke ring through a magnetic current that flows between the devices 13 to 15 and the plate 21 and obtains the same characteristic as with a micro- strip antenna having a choke ring. However, it does not need a choke ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microstrip antenna (hereinafter, also referred to as MSA) used as a receiving antenna of a GPS receiver or the like.

[0002]

2. Description of the Related Art In a GPS system, radio waves transmitted from a plurality of GPS satellites are received by a GPS antenna installed on a mobile body or the like, and the position of a reception location can be known by processing a received signal. System. SPS (Standard Positioning Servi
The positioning accuracy of ce) is about 100 m.

When the differential GPS (hereinafter, also referred to as DGPS) system is used, the positioning accuracy can be improved to several meters. The DGPS system includes a reference station installed at a point whose position is known in advance, and a mobile station which measures the position while moving to a point whose position is to be known. Both the reference station and the mobile station require a GPS antenna and a DGPS receiver, respectively, and also require a data line between the reference station and the mobile station.

As an antenna element of a GPS antenna used in this case, MSA is often used, and in order to improve positioning accuracy, MSA may be attached to a choke ring having excellent multipath removal capability. is there.

In this case, the MSA is a microstrip antenna element (also referred to as an MSA element) 11 as shown in, for example, a perspective view of FIG. 7A and a cross-sectional view of FIG.
And a plurality of choke rings 30 made of aluminum concentrically formed on the MSA element 11.

[0006]

However, the MSA attached to the choke ring is heavy due to the structure of the choke ring. Particularly, in the case of a mobile station, it is often difficult to carry the portable station because it is often carried around. There was a point.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lightweight, easily movable microstrip antenna capable of suppressing gain at a low elevation angle including the backside and suppressing cross polarization components.

[0008]

A microstrip antenna according to the present invention comprises: a microstrip antenna element including a radiation conductor formed on a surface of a dielectric substrate and a ground conductor formed on the back surface of the dielectric; And a ground plate fixedly and electrically connected to the radiating conductor, and one or more non-exciters made of a conductor provided so as to surround the radiation conductor.

In the microstrip antenna according to the present invention, a non-exciter made of a conductor is installed concentrically so as to surround the microstrip antenna element fixed on the ground plate and electrically connected thereto. Due to the magnetic current flowing between the exciter and the ground plate, an effect equivalent to that of the choke ring is obtained, and as a result, the same characteristics as those of the MSA with the choke ring are obtained. In addition, since it is sufficient to use a non-exciter and a ground plate instead of the choke ring, the weight is reduced and the portability is facilitated.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a microstrip antenna according to the present invention will be described with reference to embodiments.

FIGS. 1A and 1B are a perspective view and a sectional view, respectively, showing the structure of a microstrip antenna according to an embodiment of the present invention.

A microstrip antenna 10 according to one embodiment of the present invention includes an MSA element 11 composed of a dielectric substrate having a circular radiation conductor 12 formed on the surface and a ground conductor (not shown) formed on the back, and an MSA. A ground plate 21 fixed to the ground conductor of the element 11 and electrically connected to the ground conductor of the MSA element 11;
1. Styrofoam 22 fitted to 1 and Styrofoam 2
2 includes non-exciters 13, 14, and 15 made of disc-shaped conductors fixed at positions concentric with the MSA element 11.

The MSA element 11 has a center frequency of 1575.42 MHz (wavelength λ ₀ = 190) transmitted from a GPS satellite.
mm) of the right-handed circularly polarized wave antenna. Power is supplied from the surface of the MSA element 11 on the ground conductor side, and is usually provided on the surface of the MSA element 11 on the ground conductor side to amplify weak radio waves (about -130 dBm) from GPS satellites with low noise. The output from the feed point of the MSA element 11 is amplified at high frequency by a preamplifier (not shown).

The MSA element 11 includes a dielectric substrate formed in a circular shape, a circular radiation conductor 12 formed concentrically with the dielectric substrate on the surface of the dielectric substrate, and a dielectric substrate formed on the back surface of the dielectric substrate. And a ground conductor. As the dielectric substrate of the MSA element 11, for example, a glass cloth / Teflon double-sided printed board (PC board) having a specific dielectric constant of 2.6, a thickness of 3.2 mm, and a thickness of 35 μm of a copper foil forming the radiation conductor 12 and the ground conductor Is used. The radiation conductor 12 is formed on a glass cloth / Teflon double-sided printed circuit board (PC board) by etching, has a diameter of 66 mm, and has a frequency of 157.
Resonate at 5.42 MHz.

In order to obtain circularly polarized waves, two cuts 12A and 12B called degenerate separation elements are provided on the outer periphery of the radiation conductor 12. The feed point 1 of the right-handed circularly polarized antenna is a point where the impedance becomes 50Ω on a line inclined 45 ° counterclockwise with respect to a straight line connecting the cuts 12A and 12B constituting the degenerate separation element and the center point of the radiation conductor 12.
2C.

Next, the configuration of the MSA 10 will be described in more detail.

The ground plate 21 is formed of a cylindrical thin metal plate having a flange at the bottom and a sealed upper portion, for example, an aluminum plate having a thickness of 2 mm, and having an outer diameter of, for example, 368.5 mm ( About 2λ ₀ ). Upper seal portion of the ground plate 21 are each other by approximately λ ₀ /4(47.5mm) higher than other portions in order to install the MSA element 11, sealing the top of the higher was ground plate 21 It is attached to the portion so as to be electrically conductive to the ground conductor side of the right-handed circularly polarized MSA element 11.

[0018] In the cross-sectional shape of the bottom flange of the ground plate 21 in a stepwise manner, about λ ₀ /4(47.5m than other portions
m) A hollow cylindrical Styrofoam 22 is fitted on the ground plate 21 other than the raised portion. On the surface of the Styrofoam 22, non-exciters 13, 14, and 15 made of concentric disc-shaped conductors having different radii so as to surround the MSA element 11 are provided around the MSA element 11.
The SA element 11 is fixed so as to be located substantially on the same plane as the ground conductor surface.

Here, as described above, the ground plate 21
The cross-sectional shape of the bottom flange of the styrofoam 22
The reason why the distances to the non-exciters 13, 14, and 15 provided above are changed is that the directivity of the MSA 10 with respect to the elevation angle has a desired characteristic. The styrofoam 22 is provided to support the non-exciters 13, 14 and 15, and the styrofoam 22 has a relative dielectric constant substantially equal to that of air, and its weight is light.

Therefore, a lightweight dielectric having a large relative dielectric constant may be used instead of the polystyrene foam 22, and it is a matter of course that the use of such a dielectric can reduce the size.

The non-exciters 13, 14 and 15 are made of an aluminum plate having a thickness of 1 mm.
Has an inner diameter of 203.2 mm, an outer diameter of 216 mm, and the next non-exciter 14 has an inner diameter of 279.2 mm, an outer diameter of 292 mm,
The inner diameter of the outer non-exciter 15 is 355.7 mm, and the outer diameter is 3
It is formed to 68.5 mm.

[0022] The most important feature in the MSA10 above, apart distance of about lambda _0/4 from the bottom of the ground plate 21 through the foam 22, non exciter 13 and 14,
15 are arranged concentrically. With such a configuration, the electric field of the MSA element 11 is changed by the magnetic current flowing in the magnetic current wall formed between each of the non-exciters 13, 14, 15 and the conductor of the ground plate 21, and the choke is changed. Directivity equivalent to a ring is obtained.

FIG. 2 shows the gain directivity of the MSA element 11, and FIG. 3 shows the gain directivity of the MSA 10. 2 and 3, the solid line is the right-handed gain, and the dotted line is the left-handed gain. The zenith direction is a direction indicated by 0 degrees in FIGS. 2 and 3, the horizontal direction is a direction indicated by 90 degrees and 270 degrees in FIGS. 2 and 3, and the back side (the ground conductor side of the MSA element 11) is shown in FIGS. From 90 degrees of 180 to 180 degrees of 2
Means a range of 70 degrees. Figures 2 and 3 show low elevation
Means from around 60 degrees to around 90 degrees and from 270 degrees to around 300 degrees.

As can be seen by comparing FIG. 2 with FIG. 3, the MSA 10 is positioned above the horizontal direction (MSA element 11).
Low radiation angle up to about 30 degrees and the right-handed and left-handed gains on the back side are reduced.
Reflected by reflectors such as buildings near MSA10,
The gain for the multipath that is converted into a low elevation angle and enters the MSA 10 can be reduced. Therefore, the influence of the multipath that deteriorates the positioning accuracy can be removed, and the positioning accuracy is improved.

The structure of the MSA 10 is smaller in weight than the structure of the conventional MSA with a choke ring shown in FIG.

FIGS. 4A and 4B are a perspective view and a cross-sectional view, respectively, showing the configuration of a first modification of the microstrip antenna according to one embodiment of the present invention.

Reference numeral 10A denotes a microstrip antenna according to a first modification of the microstrip antenna 10 according to one embodiment of the present invention.

The MSA 10A is an example in which the cross-sectional shape of the bottom flange of the ground plate 21 is tapered instead of stepwise, and the other configuration is the same as the MSA 10. Even if the cross-sectional shape of the bottom flange of the ground plate 21 is tapered instead of stepwise, the distance from the non-exciters 13, 14, 15 provided on the Styrofoam 22 is changed, and the MSA is changed.
The directivity with respect to the elevation angle of 10 can be set to a desired characteristic, and the same effect can be obtained even if the bottom cross-sectional shape of the ground plate 21 is tapered instead of stepped.

FIG. 5 is a sectional view showing a configuration of a second modification of the microstrip antenna 10 according to one embodiment of the present invention.

Reference numeral 10B denotes a microstrip antenna according to a second modification of the microstrip antenna according to one embodiment of the present invention.

In the MSA 10B, in place of the MSA element 11, a circular Teflon dielectric substrate 16 and a Teflon dielectric substrate 1 on the surface of the Teflon dielectric substrate 16 are provided.
6 and a grounding conductor 111 formed on the back surface of the Teflon dielectric substrate 16. The outer diameter of the Teflon dielectric substrate 16 is equal to that of the grounding conductor 1.
11 is formed larger than the outer diameter of the non-exciter 1
3, 14 and 15 are formed using an MSA element 11A formed on the back surface of a Teflon dielectric substrate 16 by etching.

As described above, in the MSA element 11A, one Teflon dielectric substrate 16 is used, and the Teflon dielectric substrate 1 is used.
In 6, metal patterns of the non-exciters 13, 14 and 15 can be formed by etching. Further, in the second modification, the bottom section of the ground plate 21 is tapered. Since the Teflon dielectric substrate 16 is hard,
The MSA 10B does not require the styrofoam 22.

In this case, as shown in FIG. 6, by providing a plurality of through holes 17 in the Teflon dielectric substrate 16 between the non-exciters 13, 14, 15, the weight of the Teflon dielectric substrate 16 is reduced. Since the weight is reduced, the weight of the MSA 10B is advantageously reduced.

In the above description of the MSA according to the embodiment of the present invention and its modifications, the case of a GPS antenna is exemplified, but the present invention is not limited to the GPS MSA.

That is, the present invention can be applied to an MSA that needs to suppress the gain at a low elevation angle including the backside and an MSA that needs to suppress the cross polarization component.

The ground plate 21 and the non-exciter 13
The number, shape, structure, and the like of 14, 15 are not limited to the numbers, shapes, structures described in the microstrip antennas 10, 10A, and 10B according to the embodiment of the present invention and its modifications. For example, ground plate 2
1 and the exciters 13, 14, 15 are not circular in shape,
The effect of improving directivity can be obtained even with a rectangular shape. Which shape is selected can be designed based on the degree of improvement in directivity, the difficulty of manufacturing, and the like.

The shape, structure, and material of the MSA element are not limited to the shapes and structures described in the microstrip antennas 10, 10A, and 10B according to the embodiment of the present invention and its modifications. .
The radiation conductor of the MSA element may be circular or rectangular, and the shape of the degenerate separation element for making a circularly polarized antenna is irrelevant. The material of the MSA element may be a printed circuit board or ceramic.

[0038]

As described above, according to the microstrip antenna (MSA) of the present invention, a metal non-exciter is concentrically formed on a ground plate so as to surround the MSA element. Due to the installation, the directivity of the MSA element is changed by the magnetic current flowing between the non-exciter and the ground plate. As a result, it is possible to suppress the gain at the low elevation angle and the back side, and to suppress the cross polarization, and it is easier to carry because it is lighter than the MSA with the choke ring.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a microstrip antenna according to an embodiment of the present invention, where (a) is a perspective view and (b) is a cross-sectional view.

FIG. 2 is a characteristic diagram showing gain directivity of a microstrip antenna element in the microstrip antenna according to one embodiment of the present invention.

FIG. 3 is a characteristic diagram showing gain directivity of the microstrip antenna according to one embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a first modified example of the microstrip antenna according to one embodiment of the present invention,
(A) is a perspective view and (b) is a cross-sectional view.

FIG. 5 is a cross-sectional view illustrating a configuration of a second modification of the microstrip antenna according to one embodiment of the present invention.

FIG. 6 is a perspective view of a Teflon dielectric substrate in a second modification of the microstrip antenna according to one embodiment of the present invention.

7A and 7B are diagrams showing a configuration of a conventional microstrip antenna with a choke ring, wherein FIG. 7A is a perspective view and FIG. 7B is a cross-sectional view.

[Explanation of symbols]

 10, 10A, 10B Microstrip antenna 11, 11A Microstrip antenna element 12 Radiating conductor 13, 14, 15 Non-exciter 21 Ground plate 22 Styrofoam

Claims (3)

[Claims] 1. A microstrip antenna element including a radiation conductor formed on a surface of a dielectric substrate and a ground conductor formed on a back surface of the dielectric, a ground plate fixed to and electrically connected to the ground conductor. A microstrip antenna comprising one or more non-exciters formed of a conductor provided so as to surround the radiation conductor. 2. The microstrip antenna according to claim 1, wherein the non-exciter is a polystyrene foam formed so as to be fitted to a ground plate and formed so that its surface is substantially at the same position as the surface of the dielectric substrate of the microstrip element. A microstrip antenna fixed to a surface. 3. The microstrip antenna according to claim 1, wherein the non-exciter is formed on the back surface of the dielectric substrate of the microstrip element.