Patch Antenna

Abstract

To provide a patch antenna capable of improving gain on low elevation angles.SOLUTION: The patch antenna includes a dielectric member, a radiating element provided on the dielectric member, and at least one non-powered element to be grounded, provided around the dielectric member and the radiating element. Furthermore, on the periphery of the radiating element, a plurality of the non-powered elements is provided. Each of the plurality of non-powered elements is provided at a location spaced by a predetermined distance from an outer edge of the radiating element.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a patch antenna. [Background technology]

[0002] Patent Document 1 discloses a patch antenna including a ground plane, a dielectric substrate, and a radiating element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-160902 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when an antenna device that houses a patch antenna is made smaller, the area of ​​the base to which the patch antenna is grounded becomes smaller, which may result in a decrease in the gain of the patch antenna at low elevation angles.

[0005] One object of the present invention is to improve the low elevation gain of a patch antenna. Other objects of the present invention will become apparent from the description herein. [Means for solving the problem]

[0006] One aspect of the present invention is a patch antenna comprising a dielectric member, a radiating element provided on the dielectric member, and at least one parasitic element provided around the dielectric member and the radiating element and grounded.

[0007] SUMMARY OF THE DISCLOSURE One aspect of the present invention provides improved gain for a patch antenna at low elevation angles. [Brief description of the drawings]

[0008] [Figure 1] FIG. [Diagram 2] FIG. 2 is an exploded perspective view of the vehicle-mounted antenna device 10. [Diagram 3] FIG. 2 is a perspective view of a patch antenna 30. [Figure 4] 2 is a cross-sectional view of the patch antenna 30. FIG. [Diagram 5] FIG. 2 is a plan view of a patch antenna 30 using a single power supply system. [Figure 6] FIG. 2 is a plan view of a patch antenna 30 using a dual-feed system. [Figure 7] FIG. 13 is a diagram showing the relationship between the elevation angle and the average gain in the comparative patch antenna X. [Figure 8] 2 is a diagram showing the relationship between the elevation angle and the average gain in the patch antenna 30. FIG. [Figure 9] 2 is a diagram showing the relationship between the elevation angle and the average gain in the patch antenna 30. FIG. [Figure 10] 2 is a diagram showing the relationship between the elevation angle and the average gain in the patch antenna 30. FIG. [Figure 11] 2 is a diagram showing the relationship between the elevation angle and the average gain in the patch antenna 30. FIG. [Figure 12] 1 is a diagram showing the relationship between the elevation angle and the average gain of a patch antenna 30 in a single-feed system. [Figure 13] This is a diagram showing the relationship between the elevation angle and the average gain of a patch antenna X using a single feed system. [Figure 14] FIG. 2 is a cross-sectional view of a patch antenna 30A. [Figure 15] 1 is a diagram showing the relationship between the elevation angle and the average gain in a patch antenna 30A. [Figure 16] FIG. 11 is a plan view of a patch antenna 30B. [Figure 17] 13 is a diagram showing the relationship between the elevation angle and the average gain in the patch antenna 30B. [Figure 18] FIG. 2 is a perspective view of a patch antenna 30C. [Figure 19] FIG. 13 is a perspective view of a patch antenna 30D. [Figure 20] FIG. 13 is a perspective view of a patch antenna 30E. [Figure 21] FIG. 2 is a perspective view of a patch antenna 30F. [Figure 22] FIG. 1 is a perspective view of a patch antenna 30G. [Figure 23] 13 is a diagram showing the relationship between the elevation angle and the average gain of the patch antenna 30C. [Figure 24] 13 is a diagram showing the relationship between the elevation angle and the average gain of a patch antenna 30D. [Diagram 25] 13 is a diagram showing the relationship between the elevation angle and the average gain of a patch antenna 30E. [Figure 26] 11 is a diagram showing the relationship between the elevation angle and the average gain of a patch antenna 30F. [Figure 27] 1 is a diagram showing the relationship between the elevation angle and the average gain of a patch antenna 30G. [Figure 28] FIG. 13 is a perspective view of a patch antenna 30H. [Figure 29] FIG. 2 is a perspective view of a patch antenna 30I. [Diagram 30] 1 is a diagram of a radiation pattern in the main polarization plane of patch antenna X. [Diagram 31] 1 is a diagram of the radiation pattern in the cross-polarization plane of patch antenna X. [Diagram 32] 13 is a diagram showing a radiation pattern in the main polarization plane of patch antenna 30H. [Diagram 33] 13 is a diagram showing a radiation pattern in the cross polarization plane of patch antenna 30H. [Diagram 34] 1 is a diagram showing a radiation pattern in the main polarization plane of patch antenna 30I. [Diagram 35] 1 is a diagram showing a radiation pattern in the cross polarization plane of patch antenna 30I. [Diagram 36] FIG. 13 is a perspective view of a patch antenna 30J. [Figure 37] FIG. 1 is a perspective view of a patch antenna 30K. [Figure 38] FIG. 2 is a perspective view of a patch antenna 30L. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] At least the following points will become apparent from the description of this specification and the accompanying drawings.

[0010] <<<Installation position of the vehicle-mounted antenna device 10 in the vehicle 1>>> 1 is a side view of the front of a vehicle 1 to which an in-vehicle antenna device 10 is attached. Hereinafter, the front-rear direction of the vehicle to which the in-vehicle antenna device 10 is attached is defined as the X direction, the left-right direction perpendicular to the X direction is defined as the Y direction, and the vertical direction perpendicular to the X and Y directions is defined as the Z direction. In addition, the front side (front side) from the driver's seat of the vehicle is defined as the +X direction, the right side is defined as the +Y direction, and the zenith direction (upward) is defined as the +Z direction. Hereinafter, in this embodiment, the front-rear, left-right, and up-down directions of the in-vehicle antenna device 10 will be described as being the same as the front-rear, left-right, and up-down directions of the vehicle.

[0011] The vehicle-mounted antenna device 10 is housed in a cavity 4 between a roof panel 2 of a vehicle 1 and a roof lining 3 on the ceiling surface inside the vehicle compartment. Here, the roof panel 2 is made of, for example, insulating resin so that the vehicle-mounted antenna device 10 can receive electromagnetic waves (hereinafter, appropriately referred to as "radio waves").

[0012] The vehicle-mounted antenna device 10 housed in the cavity 4 is fixed to the roof lining 3 made of insulating resin with screws or the like. In this manner, the vehicle-mounted antenna device 10 is surrounded by the insulating roof panel 2 and roof lining 3. Note that, although the vehicle-mounted antenna device 10 is fixed to the roof lining 3 in this embodiment, it may be fixed to, for example, the vehicle frame or the resin roof panel 2.

[0013] In addition, since the actual space of the cavity 4 is limited, it is difficult to increase the area of ​​the base plate that functions as the ground of the vehicle-mounted antenna device 10. For this reason, when a general patch antenna is provided in the vehicle-mounted antenna device, the gain at low elevation angles may decrease. In the following, in this embodiment, a vehicle-mounted antenna device 10 including a patch antenna that can improve the gain at low elevation angles will be described.

[0014] <<<Overview of the Vehicle-Mounted Antenna Device 10>>> 2 is an exploded perspective view of the vehicle-mounted antenna device 10. The vehicle-mounted antenna device 10 is an antenna device including a plurality of antennas that operate in different frequency bands.

[0015] Base 11 is a quadrilateral metal plate used as a common ground for antennas 21 to 26 and patch antenna 30, and is placed on roof lining 3 within cavity 4. Base 11 is a thin plate that extends in all directions.

[0016] Case 12 is a box-shaped member, and the lower of the six faces is open. Moreover, case 12 is formed of insulating resin, so that radio waves can pass through case 12. Case 12 is attached to base 11 such that the opening of case 12 is closed by base 11. Therefore, antennas 21-26 and patch antenna 30 are housed in the space inside case 12.

[0017] The antennas 21 to 26 and the patch antenna 30 are mounted on the base 11 within the case 12. The patch antenna 30 is disposed near the center of the base 11, and the antennas 21 to 26 are disposed around the patch antenna 30. Specifically, the antennas 21 and 22 are disposed in front of and behind the patch antenna 30, respectively. Furthermore, the antennas 23 and 24 are disposed on the left and right sides of the patch antenna 30, respectively. Furthermore, the antenna 25 is disposed to the left of the antenna 22 and behind the antenna 23, and the antenna 26 is disposed to the right of the antenna 21 and in front of the antenna 24.

[0018] The antenna 21 is, for example, a planar antenna used in a Global Navigation Satellite System (GNSS), and receives radio waves in the 1.5 GHz band from an artificial satellite.

[0019] The antenna 22 is, for example, a monopole antenna used in a V2X (Vehicle-to-everything) system, and transmits and receives radio waves in the 5.8 GHz or 5.9 GHz band. Although the antenna 22 is described as an antenna for V2X, it may be, for example, an antenna for Wi-Fi or Bluetooth.

[0020] The antennas 23 and 24 are antennas used for, for example, LTE (Long Term Evolution) and fifth-generation mobile communication systems. The antennas 23 and 24 transmit and receive radio waves in the 700 MHz to 2.7 GHz frequency band defined by the LTE standard. In addition, the antennas 23 and 24 also transmit and receive radio waves in the Sub-6 band defined by the fifth-generation mobile communication system standard, that is, in the frequency band from 3.6 GHz to less than 6 GHz.

[0021] The antennas 25 and 26 are, for example, antennas used in a fifth generation mobile communication system, and transmit and receive radio waves in the Sub-6 band defined by the standards of the fifth generation mobile communication system.

[0022] The applicable communication standards and frequency bands of the antennas 21 to 26 are not limited to those mentioned above, and other communication standards and frequency bands may be used.

[0023] The patch antenna 30 is an antenna used for, for example, the Satellite Digital Audio Radio Service (SDARS) system. The patch antenna 30 receives left-handed circularly polarized waves in the 2.3 GHz band.

[0024] <<<Details of Patch Antenna 30>>> The patch antenna 30 will be described in detail below with reference to Fig. 3 to Fig. 6. Fig. 3 is a perspective view of the patch antenna 30, Fig. 4 is a cross-sectional view of the patch antenna 30 taken along line AA in Fig. 3, and Figs. 5 and 6 are plan views of the patch antenna 30.

[0025] The patch antenna 30 includes a circuit board 32 on which conductive patterns 31 and 33 (described later) are formed, a dielectric member 34, a radiating element 35, parasitic elements 36-39, and a shield cover 40. In the following, in this embodiment, the circuit board 32, the dielectric member 34, and the radiating element 35, which are stacked in this order in the positive direction of the Z axis, are referred to as the "main body of the patch antenna 30." In addition, four parasitic elements 36-39 are arranged around the main body of the patch antenna 30.

[0026] The circuit board 32 is a dielectric plate material made of, for example, glass epoxy resin, and has conductor patterns 31 and 33 formed on its back surface (surface facing the negative direction of the Z axis) and its front surface (surface facing the positive direction of the Z axis). The pattern 31 includes a circuit pattern 31a and a ground pattern 31b.

[0027] The circuit pattern 31a is, for example, a conductive pattern to which a signal line 45a of a coaxial cable 45 extending from an amplifier board (not shown) is connected. The braid 45b of the coaxial cable 45 is electrically connected to the ground pattern 31b by solder (not shown). The configuration for connecting the circuit pattern 31a and the radiating element 35 will be described later.

[0028] The ground pattern 31b is a conductive pattern for grounding the main body of the patch antenna 30. The ground pattern 31b is electrically connected to four pedestal portions 11a provided on the metal base 11. Here, each of the four pedestal portions 11a is formed by bending a part of the base 11 so as to support the main body of the patch antenna 30. The ground pattern 31b is grounded by electrically connecting the ground pattern 31b to the pedestal portions 11a. For example, a metallic shield cover 40 is attached to the back surface of the circuit board 32 to protect the circuit pattern 31a.

[0029] Pattern 33 formed on the front surface of circuit board 32 is a ground pattern that functions as a ground conductor plate (or ground conductor film) of patch antenna 30 and a ground for a circuit (not shown). Pattern 33 is electrically connected to ground pattern 31b via a through hole. Moreover, ground pattern 31b is electrically connected to base 11 via base 11a and a fixing screw that fixes circuit board 32 to base 11a. Therefore, pattern 33 is electrically connected to base 11.

[0030] The dielectric member 34 is a substantially quadrilateral plate-like member having sides parallel to the X-axis and sides parallel to the Y-axis. The front and back surfaces of the dielectric member 34 are parallel to the X-axis and Y-axis, with the front surface of the dielectric member 34 facing the positive direction of the Z-axis and the back surface of the dielectric member 34 facing the negative direction of the Z-axis. The back surface of the dielectric member 34 is attached to the pattern 33 by, for example, double-sided tape. The dielectric member 34 is made of a dielectric material such as ceramic.

[0031] The radiating element 35 is a conductive element having a substantially quadrilateral shape smaller than the area of ​​the front surface of the dielectric member 34, and is formed on the front surface of the dielectric member 34. In this embodiment, the normal direction of the radiation surface of the radiating element 35 is the positive direction of the Z axis. The radiating element 35 has sides 35a and 35c parallel to the Y axis and sides 35b and 35d parallel to the X axis.

[0032] Here, the term "approximately quadrilateral" refers to a shape consisting of four sides, including, for example, a square or a rectangle, and may have at least some corners cut out at an angle to the sides. Also, the "approximately quadrilateral" shape may have a notch (concave) or a protrusion (convex) on one of the sides. In other words, the "approximately quadrilateral" may have any shape that allows the radiating element 35 to transmit and receive radio waves in a desired frequency band.

[0033] The through hole 41 penetrates the circuit board 32, the pattern 33, and the dielectric member 34. A power feed line 42 that connects the circuit pattern 31a and the radiating element 35 is provided inside the through hole 41. The power feed line 42 connects the circuit pattern 31a and the radiating element 35 while being electrically insulated from the grounded pattern 33. In this embodiment, the point where the power feed line 42 is electrically connected to the radiating element 35 is defined as a power feed point 43a.

[0034] Fig. 5 is a diagram showing the position of the feed point 43a of the radiating element 35 of the single feed system. In this embodiment, as shown by the solid line in Fig. 5, the feed point 43a is provided at a position shifted in the positive direction of the X-axis from the center point 35p of the radiating element 35. However, the position of the feed point 43a is not limited thereto, and for example, as shown by the dashed and dotted line in Fig. 5, the feed point 43a may be provided at a position shifted in the positive direction of the X-axis and the negative direction of the Y-axis from the center point 35p of the radiating element 35.

[0035] The "center point 35p of the radiating element 35" refers to the center point of the outer edge shape of the radiating element 35, that is, the geometric center. The single-feed type radiating element 35 in FIG. 5 has, for example, a substantially rectangular shape with different vertical and horizontal lengths so that a desired circularly polarized wave can be transmitted and received. The "substantially rectangular" shape is included in the above-mentioned "substantially quadrilateral". Therefore, the "center point 35p of the radiating element 35" is the point where the diagonals of the radiating element 35 intersect. The "substantially rectangular" shape is included in the above-mentioned "substantially quadrilateral".

[0036] 3 to 5, the configuration in which only one feeder line, the feeder line 42, is connected to the radiating element 35 has been described, but an additional feeder line may be provided to be connected to the radiating element 35. The additional feeder line may be provided via a through hole (not shown) that penetrates the dielectric member 34 or the like, similar to the feeder line 42, and therefore a detailed description of the configuration will be omitted here.

[0037] Fig. 6 is a diagram showing the position of the feed point 43a of the radiating element 35 of the two-feed system. Note that the positions of the two feed points 43a in Fig. 6 are merely an example, and the radiating element 35 may be located in any suitable position so that it can transmit and receive the desired circularly polarized wave. Also, the radiating element 35 in Fig. 6 has, for example, a substantially square shape with equal vertical and horizontal lengths so that it can transmit and receive the desired circularly polarized wave. Note that "substantially square" is a shape that falls within the above-mentioned "substantially quadrilateral".

[0038] <<<Overview of Parasitic Elements>>> Parasitic elements 36-39 are conductive rod-like members bent into an L shape as shown in Fig. 3. Each of parasitic elements 36-39 is provided on base 11 around radiating element 35 of patch antenna 30. Since parasitic elements 36-39 are electrically connected to the base, each of parasitic elements 36-39 is grounded.

[0039] As will be described later in detail, the term "around the radiating element 35" refers to a range in which the parasitic elements 36-39 are far enough away from the outer edge of the radiating element 35 that the gain of the patch antenna 30 at a low elevation angle is higher than when the parasitic elements 36-39 are not provided. In this embodiment, the term "around the radiating element 35" refers to a range from the outer edge of the radiating element 35 to a location that is a quarter of the wavelength used. The term "wavelength used" refers to a wavelength corresponding to a desired frequency in a desired frequency band in which the patch antenna 30 is used, and specifically refers to a wavelength corresponding to the center frequency of the desired frequency band, for example.

[0040] Each of the parasitic elements 36-39 is provided spaced outward from the outer edge of the radiating element 35, and the distances from each of the parasitic elements 36-39 to the outer edge of the radiating element 35 are equal to each other. Note that, here, the outside of the radiating element 35 refers to the direction away from the center point 35p of the radiating element 35 on the base 11. Also, as will be described in detail later, by changing the distance from the parasitic elements 36-39 to the outer edge of the radiating element 35, the characteristics of the patch antenna 30 can be adjusted.

[0041] The parasitic element 36 has a support portion 36a and an extension portion 36b. The support portion 36a is provided around the main body of the patch antenna 30 in a state where it stands perpendicular to the base 11. The support portion 36a is perpendicular not only to the base 11 but also to the radiation surface of the radiating element 35. Therefore, the support portion 36a extends in the Z-axis direction.

[0042] The base end of the support portion 36a (one end of the support portion 36a) is electrically connected to the base 11 and is grounded. The extension portion 36b extends from the top of the support portion 36a (the other end of the support portion 36a) in a direction perpendicular to the support portion 36a. In this embodiment, the total length of the parasitic element 36 is equal to or less than a quarter of the wavelength used, and more preferably slightly shorter than a quarter of the wavelength used. Note that the "total length of the parasitic element" is, for example, the length along the support portion 36a and the extension portion 36b from the base end of the support portion 36a to the tip of the extension portion 36b. The base end of the support portion 36a corresponds to the "grounded end portion."

[0043] In this way, by making the total length of the grounded parasitic element 36 approximately one-fourth of the wavelength used, the parasitic element 36 functions as a director. Note that the parasitic element 36 can also be used as a director by not grounding it and making the total length of the parasitic element 36 approximately one-half of the wavelength used. However, if the parasitic element 36 is not grounded, the parasitic element 36 is not affected by the mirror effect, and as a result, its total length becomes longer. Therefore, by using the grounded parasitic element 36, the patch antenna 30 can be made smaller.

[0044] Each of the parasitic elements 37 to 39 is the same as the parasitic element 36. Specifically, the parasitic element 37 has a support portion 37a and an extending portion 37b, and the parasitic element 38 has a support portion 38a and an extending portion 38b. Furthermore, the parasitic element 39 has a support portion 39a and an extending portion 39b. Therefore, detailed description of each of the parasitic elements 37 to 39 will be omitted.

[0045] <<<Installation conditions for parasitic elements>>> Meanwhile, parasitic elements 36-39 function as directors, and radiating element 35 receives left-handed circularly polarized waves in the 2.3 GHz band. Therefore, changing the installation positions and directions of parasitic elements 36-39 affects the radio waves received by radiating element 35. For this reason, first, the installation conditions of parasitic elements 36-39 will be described with reference to Fig. 6. In Fig. 6, the rotation direction of the left-handed circularly polarized waves received by radiating element 35 is indicated by arrow A.

[0046] ==Distance from the outer edge of the radiating element to the support and extension parts== As shown in FIG. 6, the support pillars 36a to 39a are each spaced outward from the outer edge of the radiating element 35, and are parallel to the normal to the radiating element 35, that is, the Z-axis.

[0047] Furthermore, parasitic element 36 is attached so that extension portion 36b extending from the top of support portion 36a is parallel to side 35a of radiating element 35 that is closest to extension portion 36b. Therefore, in a plan view of the front surface of radiating element 35 seen from the positive direction of the Z axis, "distance D" between parasitic element 36 and radiating element 35 is the distance from extension portion 36b (or support portion 36a) to side 35a of radiating element 35 that is closest to parasitic element 36. Distance D corresponds to the "predetermined distance."

[0048] The parasitic elements 37 to 39 are disposed in the same manner as the parasitic element 36. Although details will be described later, the parasitic elements 36 to 39 are disposed on the base 11 so that the distance D between each of the parasitic elements 36 to 39 is 16 / 3 of the wavelength used. In this embodiment, the distance D between each of the parasitic elements 37 to 39 is the same, but this is not limited to this. For example, the distance D between each of the parasitic elements 37 to 39 may be different. Furthermore, a part of the distance D between each of the parasitic elements 37 to 39 may be the same.

[0049] ==About the direction of extension== As shown in Fig. 6, the extensions 36b-39b extend from the tops of the poles 36a-39a in the direction of rotation of the left-handed circularly polarized wave so as to follow the direction of rotation of the left-handed circularly polarized wave. That is, when viewed in the negative direction of the Z axis, the extensions 36b-39b extend in a counterclockwise direction from the poles 36a-39a. Note that, as will be described in detail later, by arranging the parasitic elements 36-39 in such a direction, the low elevation angle gain of the patch antenna 30 can be improved.

[0050] Furthermore, if patch antenna 30 is designed to receive right-handed circularly polarized waves, parasitic elements 36-39 may be installed so that extensions 36b-39b extend clockwise from support portions 36a-39a, respectively, when viewed in the negative direction of the Z axis.

[0051] ==About height== In this embodiment, "height" refers to, for example, the distance from the base 11 to the target. For example, in FIG. 4, the distance from the grounded base end of the support parts 36a to 39a, that is, the base 11, to the top of the support parts 36a to 39a is defined as "height H". Here, the height H of the support parts 36a to 39a is adjusted so that the height from the base 11 to the top of the support parts 36a to 39a along the Z axis direction is equal to the height from the base 11 to the radiating element 35 along the Z axis direction. Therefore, the height from the base 11 to the extension parts 36b to 39b along the Z axis direction is also equal to the height from the base 11 to the radiating element 35 along the Z axis direction. Therefore, in the patch antenna 30, the positions of the extension parts 36b to 39b in the Z axis direction are aligned with the position of the radiating element 35 in the Z axis direction, and the extension parts 36b to 39b and the radiating element 35 are on the same XY plane.

[0052] ==About the position and offset of the extension part== 6, the distance by which the target is shifted along the X-axis direction from the position of the midpoint of side 35b (or side 35d) of radiating element 35 in the X-axis direction is defined as the X-axis offset amount. Furthermore, the distance by which the target is shifted along the Y-axis direction from the position of the midpoint of side 35a (or side 35c) of radiating element 35 in the Y-axis direction is defined as the Y-axis offset amount.

[0053] 6, the offset amount in the X-axis direction of the midpoints of extensions 37b, 39b in the X-axis direction is 0 mm. That is, the positions of the midpoints of extensions 37b, 39b in the X-axis direction are aligned with the position of the midpoint of side 35b of radiating element 35 in the X-axis direction.

[0054] The offset amount in the Y-axis direction of the midpoints of the extensions 36b, 38b in the Y-axis direction is 0 mm. That is, the positions of the midpoints of the extensions 36b, 38b in the Y-axis direction are aligned with the positions of the midpoints of the sides 35a, 35c of the radiating element 35 in the Y-axis direction.

[0055] ==Standard conditions== Here, the gains of the patch antenna 30 and a comparative patch antenna (hereinafter referred to as patch antenna X) were calculated under the conditions in Table 1 (hereinafter referred to as "reference conditions"). Note that patch antenna X (not shown) is patch antenna 30 without parasitic elements 36-39, that is, an antenna using only the main body of patch antenna 30. For convenience, the simulations of patch antenna 30 and patch antenna X used models that omitted circuit pattern 31a and the like, which have little effect on gain.

[0056] [Table 1]

[0057] FIG. 7 shows the calculation results for the patch antenna X, and FIG. 8 shows the calculation results for the patch antenna 30 provided with the parasitic elements 36-39. FIG. 7 and FIG. 8 are diagrams showing the relationship between the elevation angle and the average gain. In these diagrams, the horizontal axis shows the elevation angle, and the vertical axis shows the average gain. As shown in FIG. 7, the average gains of the patch antenna X at elevation angles of 20°, 25°, and 30° are −0.7 dBic, 0.5 dBic, and 1.5 dBic. In contrast, as shown in FIG. 8, the average gains of the patch antenna 30 provided with the parasitic elements 36-39 at elevation angles of 20°, 25°, and 30° are 0.3 dBic, 1.3 dBic, and 1.2 dBic. Therefore, the patch antenna 30 provided with the parasitic elements 36-39 has a higher average gain at low elevation angles of 20° to 30° than the patch antenna X.

[0058] In this manner, the gain of the patch antenna 30 at low elevation angles is improved by providing the grounded parasitic elements 36-39 around the radiating element 35. As a result, the patch antenna 30 can efficiently receive incoming radio waves at low elevation angles.

[0059] <<<Changes in installation conditions for parasitic elements>>> Here, a case where the installation conditions of the parasitic elements are changed will be described. Note that two or more of the conditions described below may be changed and applied in combination.

[0060] ==When distance D is changed== First, the characteristics of the patch antenna 30 will be examined when the distance D is changed among the installation conditions of the parasitic elements 36 to 39. Note that various conditions of the patch antenna 30 other than the distance D (e.g., the physical size of the main part of the patch antenna 30, the power supply method, etc.) are the same as the reference conditions described above.

[0061] Here, the results of changing the distance D to 12 mm (0.093 × wavelength used), 32 mm (1 / 4 × wavelength used), and 48 mm (3 / 8 × wavelength used) are shown in Figures 9 to 11. Figures 9 to 11 are diagrams showing the relationship between the elevation angle and the average gain. In these diagrams, the horizontal axis represents the elevation angle, and the vertical axis represents the average gain. These results are compared with the results when the distance D is set to 24 mm (3 / 16 × wavelength used) (Figure 8) and the results for patch antenna X (Figure 7).

[0062] Like the patch antenna 30 with the distance D set to 24 mm, the patch antenna 30 with the distance D set to 12 mm or 32 mm has a higher average gain at a low elevation angle of 20° to 30° than the patch antenna X. However, the patch antenna 30 with the distance D set to 48 mm has a lower average gain at a low elevation angle of 20° to 30° than the patch antenna X. Therefore, in order for the extensions 36b to 39b to contribute to improving the gain at low elevation angles, it is preferable that the distance D from the extensions 36b to 39b to the outer edge of the radiating element 35 be 32 mm (a quarter of the wavelength used) or less.

[0063] ==When the power supply method is changed== Next, a case where the power supply method of the patch antenna 30 is changed from the two-feed method to the one-feed method will be described. In this case, the standard conditions were adopted except for the size and power supply method of the radiating element 35, and the gain of the patch antenna 30 and the patch antenna X of the one-feed method was calculated. The length of the sides 35a and 35c of the radiating element 35 was set to 19.9 mm, and the length of the sides 35b and 35c was set to 21.7 mm. Furthermore, in this embodiment, as shown by the two-dot chain line in FIG. 5, the power supply point 41a was set at a position shifted in the X-axis positive direction and the Y-axis negative direction from the center point 35p of the radiating element 35.

[0064] FIG. 12 is a diagram showing the calculation results for the patch antenna 30 of the single-feed system, and FIG. 13 is a diagram showing the calculation results for the patch antenna X of the single-feed system. FIG. 12 and FIG. 13 are diagrams showing the relationship between the elevation angle and the average gain. As is clear from FIG. 7, FIG. 9, FIG. 12 and FIG. 13, the patch antenna 30 of the single-feed system, like the patch antenna 30 of the dual-feed system, can more efficiently receive incoming radio waves at low elevation angles of 20° to 30° than the patch antenna X of the single-feed system and dual-feed system. Therefore, regardless of the feeding system, the patch antenna 30 having the parasitic elements 36 to 39 can improve the gain at low elevation angles.

[0065] ==Changing height H== 4, in the patch antenna 30, the extending portions 36b-39b and the radiating element 35 are on the same XY plane. However, the height H from the base 11 to the extending portions 36b-39b may be changed, and the extending portions 36b-39b may be provided on an XY plane different from the XY plane on which the radiating element 35 exists.

[0066] 14, for example, the height H of the support pillars 36a-39a is adjusted to be 9 mm, which is lower than the height (13 mm) from the base 11 to the radiating element 35. For this reason, the positions of the extensions 36b-39b in the Z-axis direction are shifted in the negative direction of the Z-axis from the position of the radiating element 35 in the Z-axis direction.

[0067] Fig. 15 is a diagram showing the calculation results for patch antenna 30A with height H changed to 9 mm under the reference conditions. As is clear from a comparison of Fig. 7, Fig. 9, and Fig. 15, patch antenna 30A, like patch antenna 30, can more efficiently receive incoming radio waves with lower elevation angles than patch antenna X.

[0068] Here, the height H is set to be lower than the height (13 mm) from the base 11 to the surface of the radiating element 15, but the height H may be set to, for example, 15 mm, which is higher than the height to the surface of the radiating element 15. For convenience, calculation results are omitted, but even in such a case, incoming radio waves at a lower elevation angle can be received more efficiently than with the patch antenna X.

[0069] Here, if the extensions 36b-39b are located higher than the radiating element 35, the parasitic elements 36-39 have a high effect of improving the gain at low elevation angles, but the gain at high elevation angles is likely to decrease. On the other hand, if the extensions 36b-39b are located lower than the radiating element 35, the parasitic elements 36-39 have a low effect of improving the gain at low elevation angles, but the gain at high elevation angles is unlikely to decrease. Therefore, by adjusting the height H, the characteristics of the patch antenna 30 can be adjusted.

[0070] Furthermore, when the positions of the extensions 36b to 39b are set to be the same as the radiation surface of the radiating element 35 or lower than the radiation surface of the radiating element 35, the height of the patch antenna 30 can be lowered. Therefore, the height of the in-vehicle antenna device 10 including the patch antenna 30 can also be lowered.

[0071] ==When the offset amount is changed== As shown in FIGS. 5 and 6, in the patch antenna 30, the offset amount in the X-axis direction and the offset amount in the Y-axis direction are both 0 mm, but these may be changed.

[0072] For example, Fig. 16 is a plan view of an example of a patch antenna 30B with a changed offset amount. Here, the position of the midpoint of the extensions 37b and 39b in the X-axis direction is shifted in the direction of rotation of the left-handed circularly polarized wave from the position of the midpoint of the sides 35b and 35d of the radiating element 35 in the X-axis direction. Also, the position of the midpoint of the extensions 36b and 38b in the Y-axis direction is shifted in the direction of rotation of the left-handed circularly polarized wave from the position of the midpoint of the sides 35a and 35c of the radiating element 35 in the Y-axis direction. Fig. 17 is a diagram showing the relationship between the elevation angle and the average gain when the offset amount in the X-axis direction and the Y-axis direction is 14 mm.

[0073] As is clear from FIGS. 7, 9 and 17, the patch antenna 30B can increase the gain at low elevation angles more than the patch antenna X, similar to the patch antenna 30 without offset.

[0074] The position of the midpoint of the extensions 37b, 39b in the X-axis direction may be shifted in the opposite direction of the rotation of the left-handed circularly polarized wave from the position of the midpoint of the sides 35b, 35d of the radiating element 35 in the X-axis direction. The position of the midpoint of the extensions 36b, 38b in the Y-axis direction may be shifted in the opposite direction of the rotation of the left-handed circularly polarized wave from the position of the midpoint of the sides 35a, 35c of the radiating element 35 in the Y-axis direction. Here, detailed calculation results are omitted, but even in such a case, the gain at low elevation angles can be improved as in FIG. 17.

[0075] Incidentally, even if an offset amount is set as in the case of patch antenna 30B, the gain at low elevation angles can be improved, but the extensions 36b-39d are outside the range of each of the sides 35a-35d of the radiating element 35. For this reason, in such a configuration, the size of patch antenna 30B becomes large. Therefore, it is preferable to set an offset amount such that each of the extensions 36b-39d falls within the range of the sides 35a-35d. By setting the offset amount in this way, the space required for the patch antenna can be reduced.

[0076] Even if the extending portions 36b to 39d are outside the range of each of the sides 35a to 35d of the radiating element 35, the space required for the patch antenna can be reduced if the extending portions 36b to 39d are within the range of each of the sides of the dielectric member 34. Therefore, it is sufficient that at least the extending portions 36b to 39d are within the range of each of the sides of the dielectric member 34.

[0077] ==When orientation is changed== 3, in the above-described patch antenna 30, the direction in which the extending portions 36b-39b extend from the support portions 36a-39a is the same as the rotation direction of the received left-handed circularly polarized wave, but is not limited to this. Note that the direction in which the extending portions 36b-39b extend from the support portions 36a-39a is simply referred to as the direction of the extending portions 36b-39b.

[0078] For example, in a patch antenna 30C shown in FIG. 18, the direction of the extensions 36b to 39b is opposite to the rotation direction of the received circularly polarized waves.

[0079] 19, the direction of extensions 37b and 38b is the same as the rotation direction of the received circularly polarized wave, whereas the direction of extensions 36b and 39b is opposite to the rotation direction of the received circularly polarized wave.

[0080] In patch antenna 30E shown in Fig. 20, the orientation of extensions 37b and 39b is opposite to the rotation direction of the received circularly polarized wave. On the other hand, the orientation of extensions 36b and 38b is the same as the rotation direction of the received circularly polarized wave. Therefore, in patch antenna 30E, the tip of extension 36b faces the tip of extension 37b, and the tip of extension 38b faces the tip of extension 39b.

[0081] 21, the extending portions 36b to 39b extend from the outside of the sides 35a to 35d closest to the extending portions 36b to 39b toward the center point 35p of the radiating element 35. In other words, the extending portions 36b to 39b extend from the outer edge of the radiating element 35 toward the center point 35p. However, the tips of the extending portions 36b to 39b are located at positions that do not overlap with the radiating element 35.

[0082] In patch antenna 30F, when viewed in the normal direction of the radiation surface of radiating element 35, i.e., in the negative direction of the Z axis, the entire extensions 36b-39b are located outside the outer edge of radiating element 35. In other words, in a plan view viewed from a direction perpendicular to the radiation surface of radiating element 35 (Z axis direction), parasitic elements 36-39 are provided on base 11 so that parasitic elements 36-39 (extensions 36b-39b) do not overlap radiating element 35. As a result, it is possible to prevent parasitic elements 36-39 from adversely affecting radio waves from radiating element 35.

[0083] In patch antenna 30G shown in FIG. 22, extending portions 36b to 39b extend in the direction opposite to center point 35p of radiating element 35 from the outside of sides 35a to 35d closest to extending portions 36b to 39b, respectively.

[0084] Here, the gains of patch antennas 30C, 30D, 30E, 30F, and 30G were calculated. Basically, the conditions other than the orientation of extensions 36b to 39b were the same as the reference conditions in Table 1. However, in patch antennas 30F and 30G in Figs. 21 and 22, the distance D from support parts 36a to 39a to the outer edge of radiating element 35 was set to 24 mm.

[0085] Fig. 23 shows the calculation results for patch antenna 30C in Fig. 18, Fig. 24 shows the calculation results for patch antenna 30D in Fig. 19, and Fig. 25 shows the calculation results for patch antenna 30E in Fig. 20. Fig. 26 shows the calculation results for patch antenna 30F in Fig. 21, and Fig. 27 shows the calculation results for patch antenna 30G in Fig. 22.

[0086] As is clear from a comparison of Figures 7 and 9 with Figures 23 to 27, the patch antennas 30C, 30D, 30E, 30F, and 30G of Figures 18 to 22, like the patch antenna 30 of Figure 3, can increase the gain at low elevation angles more than the patch antenna X.

[0087] Here, a comparison is made between patch antenna 30 shown in Fig. 3, in which extensions 36b to 39b are oriented in the direction of rotation of left-handed circularly polarized waves, and patch antenna 30C shown in Fig. 19, in which extensions 36b to 39b are oriented in the opposite direction to the direction of rotation of left-handed circularly polarized waves. As is clear from Fig. 9, which shows the calculation results for patch antenna 30, and Fig. 23, which shows the calculation results for patch antenna 30C, patch antenna 30 has a higher gain from medium to high elevation angles than patch antenna 30C.

[0088] Therefore, by aligning the extending direction of the extending portions 36b to 39b of the parasitic elements 36 to 39 with the rotation direction of the circularly polarized waves, it is possible to efficiently receive the incoming radio waves overall from low elevation angles to high elevation angles.

[0089] 23 showing the calculation results for patch antenna 30C and FIG. 24 and FIG. 25 showing the calculation results for patch antennas 30D and 30E, it is clear that patch antennas 30D and 30E can receive incoming radio waves at medium to high elevation angles more efficiently than patch antenna 30E. Therefore, if the extension direction of at least one of extension parts 36b to 39b is the same as the rotation direction of the circularly polarized wave, the gain at low elevation angles can be improved without sacrificing the gain at medium to high elevation angles.

[0090] 21 showing the calculation results for patch antenna 30F and FIG. 22 showing the calculation results for patch antenna 30G, it is clear that the radiation characteristics of patch antennas 30F and 30G are almost the same. Therefore, regardless of the direction in which extensions 36b-39b extend, extensions 36b-39b affect the gain at medium to high elevation angles, and pillars 36a-39a contribute to improving the gain at low elevation angles.

[0091] ==When receiving linearly polarized waves== The patch antenna 30 receives left-handed circularly polarized waves, but may also receive linearly polarized waves. In such a case, a single-feed method is adopted, and the feed point 41a is shifted from the center point of the radiating element 35 in the positive direction of the X-axis. The main polarization plane is a plane defined by a line connecting the center point of the radiating element 35 and the feed point, and a normal to the radiating element 35. Therefore, the main polarization plane is parallel to the XZ plane. Moreover, the sub-main polarization plane is a plane that is perpendicular to the main polarization plane and passes through the center point of the radiating element 35. Therefore, the cross polarization plane is parallel to the YZ plane.

[0092] Fig. 28 is a perspective view of a patch antenna 30H that receives linearly polarized waves. The patch antenna 30H is an antenna in which the parasitic elements 37 and 39 are eliminated from the patch antenna 30 shown in Fig. 3, and only two parasitic elements 36 and 38 are provided. The parasitic elements 36 and 38 are provided at positions facing each other across the radiating element 35 in the direction of a straight line connecting the feeding point 43a of the radiating element 35 and the center point 35P of the shape of the radiating element 35. The distance D between the parasitic elements 36 and 38 and the radiating element 35 is 24 mm (3 / 16 x wavelength used). When the patch antenna 30H receives linearly polarized waves, the main polarization plane is the XZ plane, and the parasitic elements 36 and 38 intersect with the main polarization plane.

[0093] Fig. 29 is a perspective view of a patch antenna 30I that receives linearly polarized waves. Patch antenna 30I as shown in Fig. 29 is obtained by removing parasitic elements 36 and 38 from patch antenna 30 shown in Fig. 3 and providing only two parasitic elements 37 and 38. When patch antenna 30H as shown in Fig. 29 receives linearly polarized waves, parasitic elements 37 and 39 intersect with the cross polarization plane.

[0094] The patch antenna X is similar to the patch antennas 30H and 30I, except that it does not have the parasitic elements 36 to 39. In this calculation, the various conditions other than the feeding method and polarization are the same as the reference conditions in Table 1.

[0095] Fig. 30 and Fig. 31 show the calculation results of the patch antenna X, and Fig. 32 and Fig. 33 show the calculation results of the patch antenna 30H. Fig. 34 and Fig. 35 show the calculation results of the patch antenna 30I. Here, Fig. 30, Fig. 32 and Fig. 34 are radiation patterns showing the long-distance realized gain in the main polarization plane of linearly polarized waves in a polar coordinate system. In Fig. 30, Fig. 32 and Fig. 31, the positive direction of the Z axis is set to 0°, and the positive direction of the X axis and the negative direction of the X axis are set to 90°. Fig. 31, Fig. 33 and Fig. 35 are radiation patterns showing the long-distance realized gain in the cross polarization plane of linearly polarized waves in a polar coordinate system.

[0096] 30 and 32, the radiation pattern of patch antenna 30H, i.e., the shape enclosed by curved lines, is wider in the 90° direction than the radiation pattern of patch antenna X. Also, as is clear from comparing Fig. 31 and Fig. 33, the radiation pattern of patch antenna 30H is narrower in the 90° direction than the radiation pattern of patch antenna X. For this reason, patch antenna 30H provided with parasitic elements 36 and 38 has a lower gain at low elevation angles in the cross polarization plane than patch antenna X, but a higher gain at low elevation angles in the main polarization plane.

[0097] 30 and 31 and 34 and 35, the radiation characteristics of patch antenna 30I are almost the same as those of patch antenna X. Therefore, even if parasitic elements 37 and 39 are provided, no effect of improving the gain at low elevation angles is observed.

[0098] Therefore, in order to improve the gain at low elevation angles in the main polarization plane of linearly polarized waves, it is preferable to arrange the parasitic elements 36 and 38 in positions facing each other with the radiating element 35 therebetween along the main polarization plane.

[0099] == Number of parasitic elements == In the patch antenna 30, four parasitic elements 36 to 39 are provided around the main body of the patch antenna 30, but the number of parasitic elements is not limited to this. For example, a plurality of parasitic elements may be provided on each side of the radiating element 35 of the patch antenna 30.

[0100] ==About the inclination of the support part== In patch antenna 30, support poles 36a to 39a are perpendicular to radiating element 35, but this is not limiting. For example, support poles 36a to 39a may be inclined with respect to a line perpendicular to the radiation surface of radiating element 35, that is, with respect to the Z-axis.

[0101] ==About the inclination of the extension== In the parasitic element 36, the support portion 36a and the extending portion 36b are bent from the support portion 36a to form a right angle, but this is not limited thereto, and for example, the support portion 36a and the extending portion 36b may form an acute angle or an obtuse angle. Also, each of the parasitic elements 36 to 39 may be formed by curving a rod-shaped conductive member. Therefore, "bent" may mean that it is bent.

[0102] ==About the shape of the radiating element== In the patch antenna 30, the radiating element 35 is "approximately quadrilateral", but is not limited thereto and may be, for example, a circle, an ellipse, or a polygon other than an approximately quadrilateral. When the radiating element 35 is, for example, circular, the extending portions 36b to 39b may have an arc shape along the outer edge of the radiating element 35. Even when such a radiating element or a parasitic element is used, it is possible to improve the gain at low elevation angles.

[0103] ==Number of extensions along the rotation direction== The above-mentioned patch antenna 30 has four extension parts extending along the rotation direction of the circularly polarized wave, and patch antenna 30D has two extension parts extending along the rotation direction of the circularly polarized wave, but this is not limited to this.

[0104] 36 is a diagram showing a patch antenna 30J having one extension part along the rotation direction of a circularly polarized wave. In patch antenna 30J, extension part 36b is along the rotation direction (extends along the rotation direction), but extension parts 37b to 39b extend in the opposite direction to the rotation direction.

[0105] 37 is a diagram showing a patch antenna 30K having three extensions aligned along the rotation direction of the circularly polarized wave. In patch antenna 30K, extensions 36b, 37b, and 39b are aligned along the rotation direction (extend along the rotation direction), but extension 38b extends in the opposite direction to the rotation direction. By changing the number of extensions aligned along the rotation direction of the circularly polarized wave, the characteristics of the patch antenna can be adjusted.

[0106] ==About plate-shaped parasitic elements== In the patch antenna 30, the parasitic elements 36-39 are bent rods, but for example, the parasitic elements 36-39 may be four separate plate-shaped metal members that are bent. Also, for example, as in the patch antenna 30L shown in Fig. 38, a grounded frame-shaped parasitic element 100 may be placed within a quarter of the operating frequency so as to surround the periphery of the radiating element 35. By providing such a frame-shaped parasitic element 100 around the periphery of the radiating element 35, the gain of the patch antenna 30L at low elevation angles can be improved.

[0107] Although the patch antenna 30 of the present embodiment is provided in the vehicle-mounted antenna device 10, the present invention is not limited to this. For example, the patch antenna 30 may be provided in the housing of a general shark fin antenna. Also, the patch antenna 30 may be provided in an antenna device mounted on an instrument panel. In such a case, the patch antenna 30 may be provided directly on a metal plate or the like equivalent to the base 11.

[0108] <<<<Summary>>>> The patch antenna 30 of this embodiment has been described above. For example, in the patch antennas 30 and 30L, the parasitic elements 36 to 39 and 100 are provided around the radiating element 35, that is, outside the outer edge of the radiating element 35. Therefore, by using such patch antennas 30 and 30L, it is possible to improve the gain at a low elevation angle. Furthermore, by adopting such a configuration, even if the area of ​​the ground is small, it is possible to improve the gain at a low elevation angle, and the miniaturization of the antenna device and the patch antenna is not hindered.

[0109] Also, like patch antenna 30L, a frame-shaped parasitic element 100 may be provided, but in patch antenna 30, a plurality of parasitic elements 36-39 are provided at positions spaced a distance D outward from the outer edge of radiating element 35. By providing a plurality of parasitic elements 36-39 in this manner, it is possible to improve the gain at low elevation angles.

[0110] Furthermore, in patch antenna 30, distance D between parasitic elements 36-39 is equal to or less than one-fourth of the wavelength used (the wavelength of the desired frequency band). By providing parasitic elements 36-39 at such positions, it is possible to reliably improve the gain at low elevation angles.

[0111] Moreover, the total length of the parasitic element 36 in this embodiment is equal to or less than a quarter of the frequency used (the wavelength of the desired frequency band). By setting the total length of the grounded parasitic element 36 to this length, the parasitic element 36 operates as a director. Therefore, in the patch antenna 30, the gain at low elevation angles can be improved.

[0112] Furthermore, the patch antenna 30 can improve the gain at low elevation angles not only when it receives circularly polarized waves but also when it receives linearly polarized waves. For example, the patch antenna 30H has parasitic elements 36 and 38 arranged along the main polarization plane of the radiating element 35 and facing each other across the radiating element 35. By arranging the parasitic elements 36 and 38 in such positions, the gain at low elevation angles can be improved.

[0113] Also, as described above, the patch antenna 30 can improve gain at low elevation angles even when the radiating element 35 receives circularly polarized waves.

[0114] Moreover, in the parasitic element 36, the extension portion 36b extends from the top of the support portion 36a in a bent manner relative to the support portion 36a. This makes it possible to prevent the height of the parasitic element 36 from becoming too large while keeping the overall length of the parasitic element 36 to a desired length. Therefore, by using such a parasitic element 36, the patch antenna 30 can be made smaller.

[0115] Furthermore, for example, in the patch antenna 30, the extending portions 36b to 39b extend along the rotation direction of the circularly polarized wave, so that the gain can be improved overall from low elevation angles to high elevation angles.

[0116] Moreover, the radiating element 35 is "approximately quadrilateral", and for example, the extending portion 36b is provided parallel to the closest side of the radiating element 35. Note that "parallel" includes "approximately parallel", and it is sufficient that the parasitic element 36 is placed relative to the radiating element 35 so that the effect of the parasitic element 36 can be obtained.

[0117] Moreover, the height H (distance) of the parasitic element 36 from the base 11 is approximately the same as or lower (shorter) than the height (distance) from the base 11 to the radiating element 35. Therefore, the patch antenna 30 using the parasitic element 36 can be made smaller.

[0118] Moreover, in the patch antenna 30, the parasitic elements 36 and the like are arranged so as not to overlap with the radiating element 35 in a plan view of the radiation surface of the radiating element 35 seen from the Z-axis direction. This makes it possible to prevent the radio waves of the radiating element 35 from being adversely affected.

[0119] The above-mentioned embodiment is for the purpose of facilitating understanding of the present invention, and is not intended to limit the present invention. Furthermore, the present invention can be modified or improved without departing from the spirit of the present invention, and it goes without saying that the present invention includes equivalents thereof. [Explanation of symbols]

[0120] 1 vehicle 2 Roof Panel 3 Roof lining 4 cavities 10 Vehicle-mounted antenna device 11. Base 11a Pedestal 12 cases 21~26 Antenna 30,30A~30L Patch antenna 31,33 Pattern 31a Circuit Pattern 31b Ground pattern 32 Circuit Board 34 Dielectric materials 35 Radiating element Area 35a~35d 35p center point 36 - 39, 100 non - powered elements 36a - 39a support parts 36b - 39b extension parts 41 through - hole 42 power supply wire 43a power supply point 45 coaxial cable 45a signal wire 45b braid

Claims

1. A dielectric member; a radiating element having a radiating surface provided inside an outer edge of the dielectric member; At least one parasitic element is provided around the outer edge of the dielectric member and spaced apart from the outer edge, and is grounded; Equipped with At least a part of the parasitic element is located on a plane including the radiation surface or at a position lower than the plane including the radiation surface when viewed from the side. Patch antenna.

2. A plurality of the parasitic elements are provided around the radiating element, Each of the plurality of parasitic elements is provided at a position spaced a predetermined distance from an outer edge of the radiating element. The patch antenna of claim 1 .

3. The predetermined distance is equal to or less than one-quarter of a wavelength of a desired frequency band. The patch antenna of claim 2 .

4. The parasitic element is a bent conductor whose length from the grounded end to the tip is equal to or less than a quarter of the wavelength of a desired frequency band.

4. The patch antenna according to claim 2 or 3.

5. The radiating element is an element for receiving linearly polarized electromagnetic waves, The plurality of parasitic elements are provided at positions facing each other across the radiating element in a line direction connecting a power supply point of the radiating element and a center point of the shape of the radiating element, The patch antenna according to any one of claims 2 to 4.

6. The radiating element is an element that receives a circularly polarized electromagnetic wave. A patch antenna according to any one of claims 1 to 4.

7. Further equipped with a base, The parasitic element is A support portion provided on the base; An extension portion that extends from a top portion of the support portion while being bent relative to the support portion; have A patch antenna according to any one of claims 1 to 6.

8. Further equipped with a base, The parasitic element is A support portion provided on the base; An extension portion that extends from a top portion of the support portion while being bent relative to the support portion; Have The extension portion extends from the top of the support portion along the rotation direction of the circularly polarized wave. The patch antenna according to claim 6.

9. the radiating element is generally quadrilateral in shape; The extension portion is provided parallel to a side of the radiating element. The patch antenna according to claim 7 or 8.

10. The distance from the grounded end of the support to the top is approximately the same as or shorter than the distance from the base to the position of the radiating element. The patch antenna according to any one of claims 7 to 9.

11. The parasitic element is arranged so as not to overlap the radiating element in a plan view seen from a direction perpendicular to the radiation surface of the radiating element. A patch antenna according to any one of claims 2 to 10.

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