阅读说明：本技术 贴片天线和天线装置 (Patch antenna and antenna device ) 是由 曾根孝之 于 2018-09-21 设计创作，主要内容包括：提供一种贴片天线和天线装置,通过将贴片振子设为曲面或弯曲面状,扩大指向特性中的半值角而使得能够在较宽的角度范围内进行电波的收发。具备贴片振子(10)、和与该贴片振子(10)相对的接地导体板(20),贴片振子(10)朝向与接地导体板(20)相对的一侧的相反侧凸起。贴片振子(10)的外表面(11)具有：正面部(12)；第1侧面部(13A、13B),其相对于正面部(12)分别弯折；以及第2侧面部(14A、14B),其从第1侧面部(13A、13B)分别弯折且与正面部(12)呈直角。在从正面观察贴片振子(10)时,第1侧面部(13A)和第2侧面部(14A)朝向左侧,第1侧面部(13B)和第2侧面部(14B)朝向右侧。(Provided are a patch antenna and an antenna device, wherein a patch element is formed into a curved surface or a curved surface, thereby enlarging a half-value angle in directivity characteristics and enabling transmission/reception of radio waves in a wide angle range. The patch oscillator (10) is provided with a patch oscillator (10) and a grounding conductor plate (20) which faces the patch oscillator (10), and the patch oscillator (10) is protruded toward the opposite side of the side which faces the grounding conductor plate (20). An outer surface (11) of the patch oscillator (10) has: a front face portion (12); first side surface parts (13A, 13B) which are respectively bent with respect to the front surface part (12); and 2 nd side surface parts (14A, 14B) which are respectively bent from the 1 st side surface parts (13A, 13B) and are perpendicular to the front surface part (12). When the patch oscillator (10) is viewed from the front, the 1 st side surface part (13A) and the 2 nd side surface part (14A) face to the left, and the 1 st side surface part (13B) and the 2 nd side surface part (14B) face to the right.)

1. A patch antenna is provided with:

a patch oscillator; and

a ground conductor opposite the patch vibrator,

the patch vibrator is protruded toward the opposite side of the side opposite to the ground conductor.

2. Patch antenna according to claim 1,

is convex by taking at least 1 central line as a center,

the patch oscillator has both side ends positioned at positions separated from the center line, and planes parallel to the direction of the ground conductor at the shortest distance from the both side ends intersect with or are flush with each other.

3. Patch antenna according to claim 1 or 2,

the patch vibrator is a plate-shaped member bent and bent at a central portion thereof.

4. Patch antenna according to one of the claims 1-3,

power is supplied from one end side in the center line direction of the patch vibrator.

5. Patch antenna according to one of the claims 1-4,

the wave sources are located at both ends of the patch oscillator in the center line direction.

6. Patch antenna according to one of the claims 1-5,

the patch vibrator has a ridge line.

7. Patch antenna according to one of the claims 1-6,

a dielectric is disposed between the patch vibrator and the ground conductor.

8. Patch antenna according to one of the claims 1-7,

the patch oscillator is connected with an inner conductor of a coaxial cable, and the ground conductor is connected with an outer conductor of the coaxial cable.

9. An antenna device, wherein,

a patch antenna according to any one of claims 1 to 8.

10. The antenna device according to claim 9,

the patch antenna is supported by a vehicle body so as to be vertically polarized.

Technical Field

The present invention relates to a patch antenna having a patch element having a curved surface or a curved surface, and an antenna device including the patch antenna.

Background

In a conventional patch antenna, since a patch element as a radiation electrode is planar, directivity in a direction perpendicular to the patch element is high, that is, a half-value angle (a range of a directivity angle from a peak of a gain to-3 dB) is narrow.

Disclosure of Invention

As described above, the conventional patch antenna has a narrow half-value angle, that is, a low gain on the side of the patch antenna in the direction parallel to the patch element. Therefore, the conventional patch antenna is not suitable for use in transmitting and receiving radio waves in a wide angle range.

The present invention has been made in view of such circumstances, and an object thereof is to provide a patch antenna and an antenna device which can transmit and receive radio waves in a wide angular range by enlarging a half-value angle in directivity characteristics by forming a patch element in a curved surface or a curved surface shape.

One aspect of the present invention is a patch antenna. The patch antenna is characterized by comprising a patch oscillator and a ground conductor facing the patch oscillator, wherein the patch oscillator protrudes toward the opposite side of the side facing the ground conductor.

The patch antenna may be configured to be convex with at least 1 center line as a center, end portions on both sides of the patch element may be located at positions separated from the center line, and surfaces parallel to a direction toward the ground conductor at a shortest distance from the end portions on both sides may intersect or be flush with each other.

The patch vibrator may be a plate-like member bent and bent at a central portion thereof.

Power may be supplied from one end side in the center line direction of the patch vibrator.

The wave sources may be located at both ends of the patch oscillator in the center line direction.

The patch oscillator may have an outer surface on the opposite side of the side opposite to the ground conductor, one end of the outer surface facing a 1 st direction, and the other end facing a 2 nd direction on the opposite side of the 1 st direction.

The patch element may have a ridge.

A dielectric may be provided between the patch oscillator and the ground conductor.

An inner conductor of a coaxial cable may be connected to the patch oscillator, and an outer conductor of the coaxial cable may be connected to the ground conductor.

Another aspect of the present invention is an antenna device. The antenna device is characterized by comprising the patch antenna.

The patch antenna may be supported by the vehicle body so as to be vertically polarized.

In addition, any combination of the above-described constituent elements, or a combination obtained by converting the expression of the present invention between a method, a system, and the like is also effective as an aspect of the present invention.

Effects of the invention

According to the present invention, since the patch antenna has the patch element in a curved surface or a curved surface shape, the half-value angle in the directivity characteristic can be enlarged, and further, the radio wave can be transmitted and received in a wide angle range.

Drawings

Fig. 1 is a front view showing a patch antenna portion according to embodiment 1 of the present invention.

Fig. 2 is a side view showing a patch antenna portion according to embodiment 1 of the present invention.

Fig. 3 is a rear view showing a patch antenna portion according to embodiment 1 of the present invention.

Fig. 4 is a plan view showing a patch antenna portion according to embodiment 1 of the present invention.

Fig. 5 is a side sectional view showing the overall structure of an in-vehicle antenna device including a patch antenna.

Fig. 6 is a diagram of directivity characteristics based on simulation in which the horizontal gain of the patch antenna according to embodiment 1 is compared with the horizontal gain of the comparative example (fig. 9).

Fig. 7 is a graph of a simulated VSWR based characteristic of a patch antenna.

Fig. 8 is an explanatory diagram based on a simulation showing a relationship between the length of the patch element in the front-rear direction and the half-value angle of the patch antenna.

Fig. 9 is a cross-sectional view of a horizontal plane of a patch antenna (normal patch antenna) of a comparative example, in which a length L in the front-rear direction of the patch element is 0 mm.

Fig. 10 shows a patch antenna according to embodiment 2 of the present invention, in which the length L of the patch element in the front-rear direction is 9.7mm (0.19 λ)₀Where λ 0 represents a wavelength in free space).

Fig. 11 shows a patch antenna according to embodiment 3 of the present invention, in which the length L of the patch element in the front-rear direction is 12mm (0.236 λ)₀) Cross-sectional view of the horizontal plane.

Fig. 12 shows embodiment 3 (the length L of the patch vibrator in the front-rear direction is 12mm (0.236 λ)₀) Embodiment 4 (described later) and embodiment 4 (length L in the front-rear direction of the patch vibrator is 14.5mm (0.285 λ)₀) A plot of the simulated VSWR characteristics.

Fig. 13 shows a patch antenna according to embodiment 4 of the present invention, in which the length L of the patch element in the front-rear direction is 14.5mm (0.285 λ)₀) Cross-sectional view of the horizontal plane.

Fig. 14 is a plan view of a patch antenna having a structure suitable for a coaxial cable according to embodiment 5 of the present invention, as viewed from above.

Fig. 15 is a diagram of directivity characteristics based on simulation in which the horizontal gain of the patch antenna according to embodiment 5 is compared with the horizontal gain of the comparative example (fig. 9).

Fig. 16 is a diagram of VSWR characteristics based on simulation of the patch antenna according to embodiment 5.

Fig. 17 is a side sectional view of an antenna device according to embodiment 6 of the present invention, in which a patch antenna is provided inside a front glass of a vehicle body.

Fig. 18 is an enlarged cross-sectional view of the antenna device according to embodiment 6 of the present invention.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same or equivalent constituent elements, members, processes, and the like shown in the respective drawings are denoted by the same reference numerals, and overlapping descriptions are appropriately omitted. The embodiments are illustrative, and not restrictive, and all of the features and combinations of the features described in the embodiments are not necessarily essential to the invention.

Fig. 1 to 4 are front views showing a patch antenna portion, fig. 2 is a side view of the patch antenna portion, fig. 3 is a rear view of the patch antenna portion, fig. 4 is a plan view of the patch antenna portion, and fig. 5 is a side sectional view showing an overall structure of an antenna device including a patch antenna according to embodiment 1 of the present invention.

First, the patch antenna 1 will be described with reference to fig. 1 to 4. The patch antenna 1 is used for communication in V2X (Vehicle to electric Vehicle, road Vehicle, etc.), for example. The patch antenna 1 is disposed perpendicularly (that is, in the vertical direction) to a horizontal plane (a plane perpendicular to the direction of gravity), and is for vertically polarized waves. The patch antenna 1 includes: a patch vibrator 10 as a radiation electrode; a ground conductor plate 20 facing the patch vibrator 10; a dielectric 30 interposed between the patch vibrator 10 and the ground conductor plate 20; and a coaxial cable 40 as a power supply line.

The patch oscillator 10 is obtained by bending a planar metal plate conductor into a curved surface shape (here, a curved surface shape including a shape in which a plane is bent so as to form 1 or more ridges) that is convex toward the opposite side to the side facing the ground conductor plate 20. The patch element 10 is convex with at least 1 center line as a center. The end portions on both sides of the patch oscillator 10 are located at positions separated from the center line, and the surfaces parallel to the direction toward the ground conductor plate 20 at the shortest distance from the end portions on both sides intersect with or are flush with each other. That is, the patch vibrator 10 has a plate shape bent and folded at the center portion. Specifically, the patch oscillator 10 is formed by bending a metal plate conductor so as to have 4 ridges, and the outer surface 11 not facing the ground conductor plate 20 (the surface opposite to the surface facing the ground conductor plate 20) has 5 rectangular planes defined by 4 ridges in the vertical direction (parallel to the center line). That is, the outer surface 11 of the patch vibrator 10 has: a front face portion 12; first side surface parts 13A and 13B bent with respect to the front surface part 12; and 2 nd side surface parts 14A, 14B bent from the 1 st side surface parts 13A, 13B, respectively, at right angles to the front surface part 12. In this case, the center line is parallel to and located in the middle of the two ridge lines sandwiching the front surface portion 12. When the patch oscillator 10 is viewed from the front, the 1 st side surface part 13A and the 2 nd side surface part 14A face to the left, and the 1 st side surface part 13B and the 2 nd side surface part 14B face to the right. As a result, the patch vibrator 10 has a length L (fig. 2) in a predetermined front-rear direction (direction perpendicular to the front surface portion).

The ground conductor plate 20 is formed by bending a planar metal plate conductor so as to have 4 ridges, as in the patch oscillator 10, and has portions parallel to the front surface 12, the 1 st side surface parts 13A and 13B, and the 2 nd side surface parts 14A and 14B, respectively. The ground conductor plate 20 is provided with a hole 21 in a region including a position facing the upper center of the front portion 12 of the patch oscillator 10 and the periphery thereof.

The dielectric 30 is, for example, ABS resin, and is sandwiched between the patch vibrator 10 and the ground conductor plate 20. The dielectric 30 is molded in advance in accordance with the shape of the patch oscillator 10 obtained by bending. The patch vibrator 10 and the ground conductor plate 20 are integrated with a dielectric 30 interposed therebetween, and the patch vibrator 10 is held by the ground conductor plate 20 via the dielectric 30.

The power supply conductor 19, which is a thin strip conductor (may be pin-shaped), penetrates the hole 21 without contacting the hole, and connects the internal conductor 41 of the coaxial cable 40 and the patch oscillator 10. The power supply conductor 19 may be formed by bending a strip conductor portion integral with the patch vibrator 10, for example. The outer conductor 42 of the coaxial cable 40 is sandwiched by the pair of holding pieces 22 provided to the ground conductor plate 20, and is connected to the ground conductor plate 20.

In the patch antenna 1, the feed conductor 19 is connected to the patch element 10 at the end surface of the patch element 10 (the feed point 45 is at the height position of the end surface of the patch element 10) for impedance matching with the characteristic impedance of the coaxial cable 40. The feed conductor 19 may be connected to the patch resonator 10 at a position other than the end surface of the patch resonator 10 (for example, at a position lower than the end surface) as long as impedance matching with the characteristic impedance of the coaxial cable 40 is possible. In the patch antenna 1, the feeding conductor 19 is connected to the patch element 10 at a position that becomes the center of the patch element 10 when the patch element 10 is viewed in a horizontal plane (the feeding point 45 is at a position that becomes the center of the patch element 10 when the patch element 10 is viewed in a horizontal plane). This is because, when the patch element 10 is viewed in a horizontal plane, if the feeding point 45 is located at a position offset from a position at the center of the patch element 10, the distance from the feeding point 45 to the end of the patch element 10 in the left-right direction may vary in the left-right direction, and an unnecessary resonance may occur in the patch antenna 1. As shown in fig. 1, when power is supplied from one end side in the direction of the center line of the patch oscillator 10, the wave sources are located at both ends in the direction of the center line of the patch oscillator 10. That is, in the patch antenna 1 of fig. 1, power is supplied from the upper side in the vertical direction of the patch element 10, and therefore, a wave source is generated at the upper end and the lower end in the vertical direction of the patch element 10. Even when power is supplied from the lower side in the vertical direction of the patch vibrator 10, a wave source is generated at the upper end and the lower end in the vertical direction of the patch vibrator 10.

The patch antenna 1 does not include a short-circuit conductor such as an inverted F antenna.

Fig. 5 shows an in-vehicle antenna device 60 including the patch antenna 1. An SXM antenna 81 for satellite digital broadcast reception, a GNSS (Global Navigation satellite system) antenna 82, an AM/FM broadcast reception antenna 83, and a V2X communication patch antenna 1 are mounted in this order from the front side on an antenna base 71 mounted on the roof panel, and an antenna case 72 having radio wave transparency is placed on the antenna base 71 so as to cover these antennas. In fig. 5, the vertical and longitudinal directions of the in-vehicle antenna device 60 are defined. The upper direction of the paper is up, the lower direction is down, the left direction of the paper is front, and the right direction of the paper is back.

The SXM antenna 81 and the GNSS antenna 82 are patch antennas constituting a planar antenna, and have directivity in the upward direction. The AM/FM broadcast receiving antenna 83 has a series connection of a capacitive loading element 84 of a conductor plate and a coil 85 in series. The capacitive loaded transducer 84 is, for example, serpentine. The coil 85 may be positioned at the approximate center of the in-vehicle antenna device 60 or may be offset. The patch antenna 1 for V2X communication is configured as follows: by fixing the ground conductor plate 20 to the antenna base 71, the V2X communication patch antenna 1 is vertically erected on the antenna base 71, and the front surface portion 12 of the patch element 10 faces rearward. In a state where the in-vehicle antenna device 60 is mounted on the roof panel, the patch element 10 of the patch antenna 1 is supported on the vehicle body in a substantially vertical plane, and the patch antenna 1 is used for vertical polarization.

Fig. 6 is a diagram of a directivity characteristic based on simulation, which is expressed by comparing the horizontal plane gain (solid line) of the patch antenna 1 of embodiment 1 with the horizontal plane gain (broken line) of a comparative example (discussed later in fig. 9), frequency: 5887.5MHz, main lobe gain: 4.62dB, main lobe orientation: 0 °, half-value angle (angular range from gain peak to-3 dB): 181.4 deg. In the case of fig. 5, the azimuth angle 0 ° in fig. 6 is rearward, and the half-value angle of the patch antenna 1 of embodiment 1 can be ensured to be equal to or greater than 180 ° as compared with the case where the half-value angle is narrower in the comparative example of fig. 9. The reason why the half-value angle is increased is that the patch oscillator 10 is bent to have a curved surface protruding toward the outer surface thereof, and the patch oscillator 10 has a predetermined length L in the front-rear direction. Fig. 6 is a simulation result of the case where the patch antenna 1 alone exists, but it is considered that even if the capacitive loading element 84 extends above the patch antenna 1 as shown in fig. 5, the influence on the horizontal plane directivity characteristic can be ignored.

Fig. 7 is a diagram of a VSWR characteristic based on a simulation of the patch antenna 1. As shown in fig. 7, the VSWR does not decrease at frequencies other than 5.9GHz, and no unwanted resonance occurs in the patch antenna 1 in the vicinity of 5.9 GHz.

According to the present embodiment, the following effects can be obtained.

(1) In the patch antenna 1 including the patch oscillator 10 and the ground conductor plate 20 facing the patch oscillator 10, the patch oscillator 10 is formed in a curved surface shape in which a metal plate conductor is bent so as to have 4 ridges, and has a convex surface facing the opposite side to the side facing the ground conductor plate 20, and therefore, the half-value angle can be enlarged as compared with a general patch antenna using a planar patch oscillator.

(2) In the patch oscillator 10, the opposite side to the side facing the ground conductor plate 20 is the outer surface 11, and the 1 st side surface portion 13A and the 2 nd side surface portion 14A, which are bent from the front surface portion 12 as the central portion of the outer surface 11, are shaped so as to face the left side and the 1 st side surface portion 13B and the 2 nd side surface portion 14B face the right side, so that the half-value angle can be increased to 180 ° or more.

(3) By setting the 1 st and 2 nd side surface parts 13A and 14A facing the left side and the 1 st and 2 nd side surface parts 13B and 14B facing the right side to appropriate lengths, it is possible to suppress the occurrence of unwanted resonance (resonance in the secondary mode) while maintaining the half-value angle at 180 ° or more. An explanation of this is discussed later.

(4) The outer surface 11 of the patch oscillator 10 is a polygonal surface in which the 1 st side surface parts 13A and 13B and the 2 nd side surface parts 14A and 14B are formed so as to have an edge line with respect to the front surface part 12, and has a structure suitable for connection of the coaxial cable 40. That is, the connection work of the coaxial cable 40 can be easily performed by securing the lateral width of the front portion 12 to some extent.

The reason why the patch element of the patch antenna has a curved surface or a curved surface will be described below with reference to fig. 8 to 15.

a. Enlargement of half-value angle

Fig. 8 is an explanatory diagram based on a simulation showing a relationship between the length of the patch element in the front-rear direction and the half-value angle of the patch antenna. FIG. 9 shows the length of the patch oscillator used in the simulation of FIG. 8 in the front-rear directionFig. 10 is a cross-sectional view of a horizontal plane of a patch antenna 7 (normal patch antenna) of a comparative example at 0mm, the patch antenna 2 of embodiment 2 of the present invention used in the simulation of fig. 8, and the horizontal plane at which the length L in the front-rear direction of the patch element is 9.7mm, and fig. 11 is a cross-sectional view of the horizontal plane at which the length L in the front-rear direction of the patch element is 12mm, the patch antenna 3 of embodiment 3 of the present invention used in the simulation of fig. 8. In the simulation of fig. 8, the half-value angle was obtained assuming that the operating frequency of the patch antenna of fig. 9 to 11 was 5887.5 MHz. In addition, the method is to use λ₀When the wavelength in the free space is set, the length L in the front-back direction of the patch oscillator is 9.7mm and 0.19 lambda₀Correspondingly, the length L of the patch vibrator in the front-back direction is 12mm and 0.236 lambda₀And correspondingly.

In the patch antenna 7 of the comparative example in fig. 9, both the patch element 107 and the ground conductor plate 207 are flat plates and are arranged in parallel. The length L of the patch oscillator 107 in the front-rear direction is 0mm, and the half-value angle is the smallest as seen from fig. 8.

The patch antenna 2 of embodiment 2 in fig. 10 is a plate-like shape in which the patch element 102 is bent and bent at the center portion, and the ground conductor plate 202 is bent at the center portion and arranged parallel to the patch element 102. The length L of the patch vibrator 102 in the front-rear direction is 9.7 mm. The patch oscillator 102 has a longitudinal component in the front-rear direction, and thus, as is apparent from fig. 8, the half-value angle is larger than that of the comparative example of fig. 9.

The patch antenna 3 according to embodiment 3 of fig. 11 is a plate-like element in which the patch element 103 is bent in a substantially semicircular arc shape at the center portion, and one end portion of the outer surface of the patch element 103 faces leftward and the other end portion faces rightward. The length L of the patch vibrator 103 in the front-rear direction is 12 mm. The ground conductor plate 203 is a flat plate and is arranged in parallel with the main portion of the patch vibrator 103. In this case, as shown in fig. 8, the half-value angle is further enlarged to be 180 °. Embodiment 1 described above has a structure corresponding to the length L in the front-rear direction of the patch vibrator shown in embodiment 3 being 12 mm. In the simulation of fig. 8, the lengths (creepage distances) in the horizontal cross sections of the patch oscillators shown in fig. 9 to 11 are all set to be equal. In fig. 9 to 11, the simulation of fig. 8 was performed assuming that no coaxial cable is present.

As shown in fig. 8, when the length L in the front-rear direction is increased by making the patch element curved, the half-value angle is increased, and when one end of the patch element 103 is oriented to the left and the other end is oriented to the right as in the patch antenna 3 of fig. 11, the half-value angle is 180 °. That is, in order to increase the half-value angle, it is effective to make the patch element curved and to increase the length L in the front-rear direction, that is, to make the patch element face not only the front (toward the vehicle rear in the arrangement of the antenna device 60 in fig. 5) but also the left and right sides, and by setting the length L in the front-rear direction of the patch element to an appropriate value, the half-value angle of 180 ° can be realized.

The patch vibrator may be directed only to the front and left sides or only to the front and right sides (the cross section of the patch vibrator in the horizontal plane may have an L-shape). Since the directivity of the patch antenna in the direction perpendicular to the patch element is high, the half-value angle in this case is larger than that of a planar patch element of a general patch antenna. However, the half-value angle is smaller than the patch antennas 1 and 3 of embodiments 1 and 3 in which the patch elements are directed not only to the front but also to the left and right.

b. Suppression of generation of unwanted resonance (resonance in secondary mode)

When the patch antenna for V2X communication is designed, a primary mode that resonates at a frequency of 5.9GHz for V2X communication and a secondary mode that resonates at a frequency other than 5.9GHz exist in the resonant mode of the patch antenna.

Fig. 12 is a VSWR characteristic diagram based on simulation of the patch antenna when the length L in the front-rear direction of the patch element is 12mm and 14.5 m. In the simulation of fig. 12 in which the length L in the front-rear direction of the patch element is 12mm, the patch antenna 3 of embodiment 3 of fig. 11 is used. In the simulation in which the length L in the front-rear direction of the patch element in fig. 12 is 14.5mm, the patch antenna 4 of embodiment 4 in fig. 13, which will be described later, is used. When λ 0 is a wavelength in a free space, the length L in the front-rear direction of the patch oscillator is 12mm and 0.236 λ₀Correspondingly, the length L of the patch vibrator in the front-back direction is 14.5mm and 0.285 lambda₀And correspondingly.

Fig. 13 is a cross-sectional view of embodiment 4 and a horizontal plane of the patch antenna 4 used in the simulation in which the length L in the front-rear direction of the patch element of fig. 12 is 14.5 mm. The patch antenna 4 according to embodiment 4 of fig. 13 is a plate-like element in which the patch element 104 is bent in a substantially semicircular arc shape at the center portion, and one end portion of the outer surface of the patch element 104 faces the left direction and the other end portion faces the right direction. The length L of the patch vibrator 104 in the front-rear direction is 14.5 mm. The ground conductor plate 204 is a flat plate and is arranged in parallel with the main portion of the patch vibrator 104.

In the case of embodiment 4, the radius of curvature of the patch vibrator 104 is the same as that of the patch vibrator 103 in embodiment 3 of fig. 11. However, in order to make the length L of the patch element 104 in the front-rear direction larger than the patch element 103 in fig. 11, the length of the patch antenna 4 in the cross section of the horizontal plane (in other words, the creepage distance of the patch element 104) is longer than the length of the patch antenna 3 in fig. 11 (creepage distance of the patch element 103). Therefore, as shown in fig. 12, when the length L in the front-rear direction of the patch vibrator is 12mm (in the solid line), the VSWR does not decrease at frequencies other than 5.9GHz, the main mode is dominant, and no unwanted resonance (resonance in the secondary mode) occurs in the vicinity of the main mode. On the other hand, when the length L in the front-rear direction of the patch oscillator is 14.5mm (in the case of a broken line), the influence of the secondary mode becomes strong, the characteristics of the primary mode deteriorate, and it can be confirmed that resonance is not required.

As is clear from the results of fig. 12 and 13, in order to suppress the occurrence of unwanted resonance, the length L in the front-back direction of the patch element may be shortened (not longer than necessary), that is, the length of the patch antenna in the cross section of the horizontal plane may be shortened (not longer than necessary).

c. Presence of coaxial cable

In the comparative example of fig. 9, the embodiment 2 of fig. 10, and the embodiment 3 of fig. 11, the simulation of fig. 8 was performed without the coaxial cable, but the patch antenna needs to be electrically connected with a coaxial cable for feeding power. Fig. 14 is a plan view of the patch antenna 5 of embodiment 5, which is suitably configured to be supplied with power by the coaxial cable 40, as viewed from above. In this case, the patch antenna 5 includes: a patch vibrator 105; a ground conductor plate 205 facing the patch vibrator 105; a dielectric 305 interposed between the patch vibrator 105 and the ground conductor plate 205; and a coaxial cable 40 as a power supply line.