JP2024047278A - Planar Antenna Device - Google Patents

Abstract

A planar antenna device that expands a beam width is provided. The planar antenna device 10 includes a ground conductor 1, a dielectric substrate 2, a conductive excitation patch 3, a conductive first parasitic patch 4a and a second parasitic patch 4b, and a plurality of first conductors 6a and second conductors 6b. The dielectric substrate is provided on the ground conductor. The excitation patch is provided on the surface of the dielectric substrate opposite the ground conductor, and the length is defined so as to resonate at a predetermined frequency. The first parasitic patch is provided on the surface of the dielectric substrate opposite the ground conductor in a first region spaced apart from the excitation patch along a direction that defines the length of the excitation patch. The second parasitic patch is provided spaced apart from the excitation patch and cooperates with the first parasitic patch to sandwich the excitation patch. The first conductor electrically connects the first parasitic patch to the ground conductor, and the second conductor electrically connects the second parasitic patch to the ground conductor. [Selected figure] Figure 2

Description

An embodiment of the present invention relates to a planar antenna device.

A patch antenna, an example of a planar antenna, has a plate-shaped radiating element and a ground conductor arranged on the front and back sides of a dielectric substrate. Generally, a rectangular radiating element is used because it is easy to design and manufacture and provides good radiation characteristics.

Japanese Patent Application Laid-Open No. 3-157005

The problem that this invention aims to solve is to provide a planar antenna device that can expand the beam width.

According to an embodiment, the planar antenna device has a ground conductor, a dielectric substrate provided on the ground conductor, a conductive excitation patch, a conductive first non-excitation patch, a conductive second non-excitation patch, a plurality of first conductors, and a plurality of second conductors. The excitation patch is provided on the dielectric substrate on the side opposite the ground conductor, and the length is defined so as to resonate at a predetermined frequency. The first non-excitation patch is provided on the dielectric substrate on the side opposite the ground conductor in a first region spaced apart from the excitation patch along a direction defining the length of the excitation patch. The second non-excitation patch is provided so as to sandwich the excitation patch in cooperation with the first non-excitation patch. The plurality of first conductors electrically connect the first non-excitation patch and the ground conductor. The plurality of second conductors electrically connect the second non-excitation patch and the ground conductor.

1 is a schematic perspective view showing a planar antenna device according to an embodiment. FIG. 2 is a schematic cross-sectional view of the position indicated by the reference symbol II in FIG. 1 . 11 is a graph showing an example of the E-plane radiation pattern (normalized gain) of the planar antenna device according to the embodiment and a planar antenna device of a comparative example. 11 is a graph showing an example of radiation patterns (normalized gain) on the H plane of the planar antenna device according to the embodiment and a planar antenna device of a comparative example. FIG. 13 is a diagram showing a first modified example of the planar antenna device according to the embodiment. FIG. 13 is a diagram showing a second modified example of the planar antenna device according to the embodiment.

The planar antenna device 10 according to one embodiment will be described with reference to Figures 1 to 4.

Figure 1 shows a schematic perspective view of a planar antenna device 10 according to this embodiment. As shown in Figure 1, an xyz orthogonal coordinate system is defined. The x-axis is along the length L of the rectangular excitation patch 3 described below. The y-axis is along the width W of the excitation patch 3. The z-axis is along the normal to the surface of the excitation patch 3.

Figure 2 shows a cross section of the planar antenna device 10 along an imaginary plane indicated by the symbol II in Figure 1, which includes the feed point 7.

As shown in Figures 1 and 2, the planar antenna device 10 has a ground conductor 1, a dielectric substrate 2, an excitation patch 3, a pair of non-excitation patches (a first non-excitation patch 4a and a second non-excitation patch 4b), a plurality of first conductors 6a, a plurality of second conductors 6b, and a feed point 7.

The ground conductor 1 is, for example, a rectangular, thin, conductive conductor made of, for example, copper foil.

In this embodiment, the dielectric substrate 2 is formed, for example, rectangular and of the same size as the ground conductor 1. The dielectric substrate 2 may be formed smaller than the ground conductor 1. It is preferable that the thickness of the dielectric substrate 2 along the z-axis is thicker than that of the ground conductor 1.

The excitation patch 3 is formed as, for example, a rectangular conductor that is smaller than the ground conductor 1 and the dielectric substrate 2. The excitation patch 3 is formed, for example, from copper foil. The excitation patch 3 is placed on the surface of the dielectric substrate 2 opposite the ground conductor 1. It is preferable that the excitation patch 3 be placed approximately in the center of the surface of the dielectric substrate 2 opposite the ground conductor 1.

The excitation patch 3 resonates at a predetermined frequency f. As an example, the resonance frequency may be in the MHz band or the GHz band. Here, as shown in FIG. 1, the length of the excitation patch 3 is L and the width is W. In this case, it is preferable that the length L is equal to or approximately equal to an integer multiple of a half wavelength of the wavelength λ corresponding to the resonance frequency f.

The first non-excited patch 4a and the second non-excited patch 4b are provided on the surface of the dielectric substrate 2 opposite to the surface on which the ground conductor 1 is provided, similar to the excitation patch 3. The first non-excited patch 4a and the second non-excited patch 4b are formed, for example, as rectangular conductors. The first non-excited patch 4a and the second non-excited patch 4b are formed, for example, from copper foil, similar to the excitation patch 3. The first non-excited patch 4a and the second non-excited patch 4b are formed, for example, from the same material, with the same shape and size. The first non-excited patch 4a and the second non-excited patch 4b are formed to the same width as the top surface of the dielectric substrate 2 in FIG. 1.

The first non-excitation patch 4a is provided in a first region (a region above the excitation patch 3 in FIG. 1) that is spaced apart from the excitation patch 3 along a direction (x-axis direction) that defines the length L of the excitation patch 3. The first non-excitation patch 4a is spaced apart a predetermined distance from the excitation patch 3 in the +x-axis direction relative to the excitation patch 3.

The second non-excitation patch 4b is provided in a second region (a second region (a region below the excitation patch 3 in FIG. 1) spaced apart from the excitation patch 3 along a direction (x-axis direction) that defines the length L of the excitation patch 3) on the opposite side of the excitation patch 3 from the first region, so as to cooperate with the first non-excitation patch 4a to sandwich the excitation patch 3. The second non-excitation patch 4b is spaced apart from the excitation patch 3 by a predetermined distance in the -x-axis direction with respect to the excitation patch 3.

It is preferable that the distance between the first non-excitation patch 4a and the excitation patch 3, and the distance between the second non-excitation patch 4b and the excitation patch 3 are equal. Therefore, a pair of non-excitation patches (the first non-excitation patch 4a and the second non-excitation patch 4b) are arranged on the dielectric substrate 2 at a distance from the excitation patch 3 and sandwich the excitation patch 3.

It is also preferable that the first non-excitation patch 4a and the second non-excitation patch 4b are arranged symmetrically with respect to the center (centroid) of the excitation patch 3. It is also preferable that the first non-excitation patch 4a and the second non-excitation patch 4b are arranged parallel to and symmetrically with respect to a plane perpendicular to the E-plane (electric field plane) from the center (centroid) of the excitation patch 3.

It is preferable that the distance between the first non-excitation patch 4a and the excitation patch 3, and the distance between the second non-excitation patch 4b and the excitation patch 3, are smaller than the wavelength λ (one wavelength) corresponding to the resonant frequency f.

In the first non-excitation patch 4a, a plurality of through holes (penetrating holes) 5a are formed, for example, at equal intervals along the y axis near the center along the x axis. Similarly, in the second non-excitation patch 4b, a plurality of through holes (penetrating holes) 5b are formed, for example, at equal intervals along the y axis near the center along the x axis. It is preferable that the plurality of through holes 5a in the first non-excitation patch 4a and the plurality of through holes 5b in the second non-excitation patch 4b are formed to be the same size.

The first conductors 6a are connected between the multiple through holes 5a of the first non-excitation patch 4a and the ground conductor 1. The multiple through holes 5a form a ring that electrically connects one end of the first conductor 6a to the first non-excitation patch 4a, for example, by fitting it. The other end of the first conductor 6a is abutted or fixed to the ground conductor 1. The first conductor 6a penetrates the dielectric substrate 2. For this reason, the multiple first conductors 6a are formed, for example, in a shaft (pin) shape. Therefore, the multiple first conductors 6a each extend parallel to the normal (z-axis) to the surface of the dielectric substrate 2 of the excitation patch 3. The multiple first conductors 6a are formed, for example, of copper or a copper alloy. Therefore, the first non-excitation patch 4a and the ground conductor 1 are electrically connected by the multiple first conductors 6a. That is, the multiple first conductors 6a electrically connect the first non-excited patch 4a, which is one of a pair of non-excited patches, to the ground conductor 1.

The second conductor 6b is connected between the multiple through holes 5b of the second non-excitation patch 4b and the ground conductor 1. The multiple through holes 5b form a ring that electrically connects one end of the second conductor 6b to the second non-excitation patch 4b, for example, by fitting it. The other end of the second conductor 6b is abutted or fixed to the ground conductor 1. The second conductor 6b penetrates the dielectric substrate 2. For this reason, the multiple second conductors 6b are formed, for example, in a shaft (pin) shape. Therefore, the multiple second conductors 6b each extend parallel to the normal (z-axis) to the surface of the dielectric substrate 2 of the excitation patch 3. The multiple second conductors 6b are formed, for example, of copper or a copper alloy. Therefore, the second non-excitation patch 4b and the ground conductor 1 are electrically connected by the multiple second conductors 6b. That is, the multiple second conductors 6b electrically connect the second non-excited patch 4b, which is the other of the pair of non-excited patches, to the ground conductor 1.

Therefore, the first non-excited patch 4a is electrically contacted by a first conductor 6a provided between the ground conductor 1 and the multiple through holes 5a at a position spaced a predetermined distance from the excitation patch 3, parallel to a plane perpendicular to the E-plane. Similarly, the second non-excited patch 4b is electrically contacted by a second conductor 6b provided between the ground conductor 1 and the multiple through holes 5b at a position spaced a predetermined distance from the excitation patch 3 on the opposite side to the first non-excited patch 4a, parallel to a plane perpendicular to the E-plane.

The feed point 7 is positioned at a position offset toward the second non-excited patch 4b along the x-axis direction with respect to the centroid of the excitation patch 3. This is to obtain matching with the feed line 7a, whose characteristic impedance is, for example, 50 Ω. The feed point 7 is not positioned at the centroid of the excitation patch 3, but in this embodiment, it is preferable to position the feed point 7 near the centroid. It is preferable to position the feed point 7 at the center or approximately the center of the width W of the excitation patch 3.

Next, we will explain the operation of the planar antenna device 10 described above.

When power is supplied to the excitation patch 3 from the power supply point 7, the excitation patch 3 resonates at a predetermined frequency f. Then, radio waves are emitted from the excitation patch 3. The radiation of radio waves from the excitation patch 3 generates induced currents in the first non-excited patch 4a and the second non-excited patch 4b. Therefore, re-radiation occurs from the first non-excited patch 4a and the second non-excited patch 4b.

The radiation pattern of radio waves from the planar antenna device 10 according to this embodiment is a combination of the radiation pattern of the excitation patch 3 and the re-radiation patterns from the first non-excited patch 4a and the second non-excited patch 4b. Therefore, the radiation pattern of radio waves from the planar antenna device 10 according to this embodiment has a wider radio wave beam width than the radiation pattern of the excitation patch 3 by the amount of the first non-excited patch 4a and the second non-excited patch 4b.

As an example, Figures 3 and 4 show the radio wave radiation patterns superimposed when the first non-excited patch 4a and the second non-excited patch 4b are present (planar antenna device 10 of this embodiment) and when the first non-excited patch 4a and the second non-excited patch 4b are not present (planar antenna device of the comparative example) at an operating frequency f of 9.5 GHz. Note that Figure 3 shows the radiation pattern from -90° to +90° on the E plane (electric field plane), and Figure 4 shows the radiation pattern from -90° to +90° on the H plane (magnetic field plane).

In general, patch antennas as planar antenna devices have a relatively narrow beam width in the radiation pattern of the elements, approximately 90° in the E-plane and approximately 80° in the H-plane.

As shown in FIG. 3, in the E-plane, when a pair of parasitic patches 4a, 4b is used, the beam width is expanded in the range of −90° to +90° compared to when a pair of parasitic patches 4a, 4b is not used.
The reason why the graph of the radiation pattern in FIG. 3 is not symmetrical with respect to 0° is that, as described above, the feeding point 7 is shifted in the x-axis direction from the centroid of the exciting patch 3 toward the second non-exciting patch 4b in order to obtain matching with the feeding line 7a having a characteristic impedance of, for example, 50Ω.

In addition, as shown in FIG. 4, when a pair of non-excited patches 4a, 4b is used not only on the E-plane but also on the H-plane, the beam width is expanded in the range of −90° to +90° compared to when a pair of non-excited patches 4a, 4b is not used.
The graph of the radiation pattern in FIG. 4 is symmetrical with respect to 0° because the feed point 7 is disposed at the center of the excitation patch 3 in the width direction.

As described above, the radiation beam width in the E-plane can be expanded by using a planar antenna device 10 having a first non-excited patch 4a and a second non-excited patch 4b, each of which is electrically connected to the ground conductor 1, according to this embodiment. Also, the radiation beam width in the H-plane can be expanded by using a planar antenna device 10 having a first non-excited patch 4a and a second non-excited patch 4b, each of which is electrically connected to the ground conductor 1, according to this embodiment.

(First Modification)
The structure of the planar antenna device 10 shown in FIG. 5 is basically the same as that of the planar antenna device 10 shown in FIGS.

The width of the first non-excited patch 4a of the planar antenna device 10 of the first modified example is smaller than the width W of the excited patch 3. Similarly, the width of the second non-excited patch 4b of the planar antenna device 10 of the first modified example is smaller than the width W of the excited patch 3.

The planar antenna device 10 may be formed in this manner. That is, radio waves can be not only radiated from the excitation patch 3, but also re-radiated from the first non-excited patch 4a and the second non-excited patch 4b. Therefore, the radiation pattern of radio waves from the planar antenna device 10 according to this modification is a pattern that combines the radiation pattern of the excitation patch 3 and the re-radiation patterns from the first non-excited patch 4a and the second non-excited patch 4b. Therefore, the radiation pattern of radio waves from the planar antenna device 10 according to this modification can expand the beam width of radio waves compared to the radiation pattern of the excitation patch 3 by the amount of the first non-excited patch 4a and the second non-excited patch 4b.

Therefore, in this modified example, a planar antenna device 10 is provided that can expand the beam width even if the width of the first non-excited patch 4a and the second non-excited patch 4b is made smaller than the width W of the excited patch 3.

In the above-described embodiment and this modified example, the first non-excitation patch 4a and the second non-excitation patch 4b are described as being rectangular, but various shapes such as an appropriate polygon, circle, ellipse, and others are acceptable. Also, the excitation patch 3 is described as being rectangular, but any appropriate shape is acceptable.

(Second Modification)
As shown in Fig. 6, the planar antenna device 10 has first parasitic patches 4a, 4a1, 4a2 and second parasitic patches 4b, 4b1, 4b2. The first parasitic patches 4a, 4a1, 4a2 and the second parasitic patches 4b, 4b1, 4b2 are formed symmetrically with respect to the centroid of the excited patch 3. In this modification, the planar antenna device 10 has three pairs of parasitic patches (the first parasitic patches 4a, 4a1, 4a2 and the second parasitic patches 4b, 4b1, 4b2).

The first non-excitation patches 4a, 4a1, and 4a2 are arranged in a direction along the width W of the excitation patch 3, i.e., in the y-axis direction. The first non-excitation patch 4a1 is arranged on an extension line of a position along the left end of the width W of the excitation patch 3 in FIG. 6 (first end in the width direction of the excitation patch 3), i.e., in a position along the x-axis direction, and the first non-excitation patch 4a2 is arranged on an extension line of a position along the right end (second end in the width direction of the excitation patch 3), i.e., in a position along the x-axis direction.

The second non-excitation patches 4b, 4b1, and 4b2 are arranged in a line along the width W of the excitation patch 3, i.e., along the y-axis direction. The second non-excitation patch 4b1 is arranged on an extension of the left end of the width W of the excitation patch 3 in FIG. 6 (first end in the width direction of the excitation patch 3), i.e., along the x-axis direction, and the second non-excitation patch 4b2 is arranged on an extension of the right end (second end in the width direction of the excitation patch 3), i.e., along the x-axis direction.

Therefore, the pair of the first non-excited patch 4a and the second non-excited patch 4b is arranged to sandwich the excitation patch 3. The pair of the first non-excited patch 4a1 and the second non-excited patch 4b1 is arranged to sandwich the excitation patch 3. The pair of the first non-excited patch 4a2 and the second non-excited patch 4b2 is arranged to sandwich the excitation patch 3. Alternatively, the pair of the first non-excited patch 4a1 and the second non-excited patch 4b2 is arranged to sandwich the excitation patch 3, and the pair of the first non-excited patch 4a2 and the second non-excited patch 4b1 is arranged to sandwich the excitation patch 3.

The planar antenna device 10 may be formed in this manner. That is, radio waves can be not only radiated from the excitation patch 3, but also re-radiated from the first non-excited patch 4a, 4a1, 4a2 and the second non-excited patch 4b, 4b1, 4b2. Therefore, the radiation pattern of radio waves of the planar antenna device 10 according to this modification is a pattern in which the radiation pattern of the excitation patch 3 and the re-radiation patterns from the first non-excited patch 4a and the second non-excited patch 4b are combined. Therefore, the radiation pattern of radio waves of the planar antenna device 10 according to this modification can expand the beam width of radio waves compared to the radiation pattern of the excitation patch 3 by the amount of the first non-excited patch 4a, 4a1, 4a2 and the second non-excited patch 4b, 4b1, 4b2.

Therefore, in this modified example, a planar antenna device 10 is provided that can expand the beam width even if there are multiple pairs of patches, such as the first non-excited patches 4a, 4a1, and 4a2 and the second non-excited patches 4b, 4b1, and 4b2.

At least one of the embodiments described above can provide a planar antenna device 10 that can expand the beam width.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

1...ground conductor, 2...dielectric substrate, 3...excited patch, 4a...first non-excited patch, 4b...second non-excited patch, 5a, 5b...through hole, 6a...first conductor, 6b...second conductor, 7...feed point, 7a...feed line, 10...planar antenna device.

Claims (5)

A ground conductor;
a dielectric substrate provided on the ground conductor;
a conductive excitation patch provided on the dielectric substrate on a surface opposite to the ground conductor, the length of the conductive excitation patch being determined so as to resonate at a predetermined frequency;
a conductive first non-excitation patch provided in a first region on the dielectric substrate on a surface opposite to the ground conductor and spaced apart from the excitation patch along a direction defining a length of the excitation patch;
a conductive second parasitic patch spaced apart from the excitation patch and arranged to sandwich the excitation patch in cooperation with the first parasitic patch;
a plurality of first conductors electrically connecting the first parasitic patch and the ground conductor;
a plurality of second conductors electrically connecting the second parasitic patch and the ground conductor. the first conductors each pass through the dielectric substrate and are connected to the ground conductor;
the second conductors each pass through the dielectric substrate and are connected to the ground conductor;
2. A planar antenna device according to claim 1. The planar antenna device according to claim 2, wherein the plurality of first conductors and the plurality of second conductors each extend parallel to a normal to a surface of the excitation patch on the dielectric substrate. The planar antenna device according to claim 1 or 2, wherein the distance between the first non-excited patch and the excited patch is equal to the distance between the second non-excited patch and the excited patch. A ground conductor;
a dielectric substrate provided on the ground conductor;
a conductive excitation patch provided on the dielectric substrate on a surface opposite to the ground conductor, the length of the conductive excitation patch being determined so as to resonate at a predetermined frequency;
At least a pair of conductive non-excitation patches are provided on the dielectric substrate on a surface opposite to the ground conductor, spaced apart from the excitation patch, and sandwiching the excitation patch along a direction that defines a length of the excitation patch;
a plurality of first conductors electrically connecting one of the at least one pair of parasitic patches to the ground conductor;
a plurality of second conductors electrically connecting the other of the at least one pair of parasitic patches to the ground conductor.