patch antenna

Abstract

To provide a patch antenna that can improve gain at low elevation angles.SOLUTION: A patch antenna includes a radiating element, a first dielectric member provided with the radiating element, and at least one second dielectric member provided around the first dielectric member. The dielectric constant of the second dielectric member is higher than the dielectric constant of the first dielectric member. Also, the dielectric constant of the second dielectric member is 30 or higher.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 conductor plate, a dielectric substrate, and a radiating element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-160902 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the antenna device that houses the patch antenna is made smaller, the area of ​​the base where 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 angle 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 radiating element, a first dielectric member on which the radiating element is provided, and at least one second dielectric member provided around the first dielectric member. [Effects of the Invention]

[0007] According to one aspect of the present invention, the gain of a patch antenna at low elevation angles is improved. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a side view of the vehicle 1. [Figure 2] FIG. 2 is an exploded perspective view of the vehicle-mounted antenna device 10. [Figure 3] FIG. 2 is a perspective view of a patch antenna 30. [Figure 4] FIG. 2 is a cross-sectional view of the patch antenna 30. [Figure 5] FIG. 1 is a plan view of a patch antenna 30 of a single-feed type. [Figure 6] FIG. 1 is a plan view of a patch antenna 30 using a dual feed system. [Figure 7] FIG. 10 is a plan view of a patch antenna 30X of a comparative example. [Figure 8] 10A and 10B are diagrams showing the electric field distributions of a patch antenna 30X of a comparative example and the patch antenna 30 of this embodiment. [Figure 9] 10 is a diagram showing the relationship between the elevation angle and the average gain in a patch antenna 30X of the comparative example. [Figure 10] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain in the patch antenna 30 (εr2=20). [Figure 11] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain in the patch antenna 30 (εr2=30). [Figure 12] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain in the patch antenna 30 (εr2=40). [Figure 13] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain in the patch antenna 30 (εr2=2). [Figure 14] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain in the patch antenna 30 (εr2=7.82). [Figure 15] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain in the patch antenna 30 (T=5 mm). [Figure 16] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain in the patch antenna 30 (T=3 mm). [Figure 17] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain of the patch antenna 30 (T=7 mm). [Figure 18]FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain in the patch antenna 30 (T=8 mm). [Figure 19] FIG. 2 is a plan view of a patch antenna 30A. [Figure 20] 10 is a diagram showing the relationship between the elevation angle and the average gain in a patch antenna 30A. [Figure 21] FIG. 10 is a plan view of a patch antenna 30B. [Figure 22] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain in the patch antenna 30B. [Figure 23] FIG. 10 is a plan view of a patch antenna 30C. [Figure 24] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain in the patch antenna 30C. [Figure 25] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain of a patch antenna 30A (W=1 mm). [Figure 26] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain of a patch antenna 30A (W=4 mm). [Figure 27] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain of a patch antenna 30A (W=8 mm). [Figure 28] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain of a patch antenna 30A (W=10 mm). [Figure 29] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain of the patch antenna 30A (D=15 mm). [Figure 30] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain of the patch antenna 30A (D=10 mm). [Figure 31] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain of the patch antenna 30A (D=5 mm). [Figure 32] FIG. 10 is a plan view of a patch antenna 30D. [Figure 33] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain in a patch antenna 30D. [Figure 34] FIG. 10 is a plan view of a patch antenna 30E. [Figure 35] FIG. 10 is a diagram showing the relationship between the elevation angle and the average gain of a patch antenna 30E. DETAILED DESCRIPTION OF THE INVENTION

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

[0010] <<<Installation position of the in-vehicle 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-to-rear direction of the vehicle to which the in-vehicle antenna device 10 is attached is defined as the X direction, the left-to-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. Furthermore, the front side (front side) from the driver's seat of the vehicle is defined as the +X direction, the right side as the +Y direction, and the zenith direction (upward) as the +Z direction. Hereinafter, in this embodiment, the front-to-rear, left-to-right, and up-to-down directions of the in-vehicle antenna device 10 will be described as being the same as the front-to-rear, left-to-right, and up-to-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 referred to as "radio waves" as appropriate).

[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 the roof lining 3. In this embodiment, the vehicle-mounted antenna device 10 is fixed to the roof lining 3, but it may also be fixed to the vehicle frame or the resin roof panel 2, for example.

[0013] Furthermore, 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, if 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] <<<Outline 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, and includes a base 11, a case 12, antennas 21 to 26, and a patch antenna 30.

[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 its six faces is open. Furthermore, case 12 is made of insulating resin, so radio waves can pass through case 12. Case 12 is attached to base 11 so that the opening of case 12 is closed by base 11. Therefore, antennas 21 to 26 and patch antenna 30 are housed in the space inside case 12.

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

[0018] The antenna 21 is, for example, a planar antenna used for 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 band or 5.9 GHz band. Although the antenna 22 is described as an antenna for V2X, it may also be an antenna for Wi-Fi or Bluetooth, for example.

[0020] The antennas 23 and 24 are antennas for telematics, and are used, for example, in 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. Furthermore, 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, the frequency band from 3.6 GHz to less than 6 GHz.

[0021] The antennas 25 and 26 are antennas for telematics, and are antennas used in, for example, a fifth generation mobile communication system. The antennas 25 and 26 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 also be used.

[0023] The patch antenna 30 is an antenna used in, 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. Note that SDARS satellites are geostationary satellites. Therefore, in order to receive SDARS signals, particularly in the service area of ​​northern Canada (high latitude region), the patch antenna 30 is required to have good gain even at low elevation angles.

[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 is configured to include a circuit board 32 on which conductive patterns 31 and 33 (described later) are formed, a first dielectric member 34, a radiating element 35, a second dielectric member 36, and a shield cover 50. In the following, in this embodiment, the circuit board 32, the first dielectric member 34 and the second dielectric member 36, and the radiating element 35, which are stacked in this order in the positive direction of the Z axis, will be referred to as 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, with conductive patterns 31 and 33 formed on its back surface (surface facing the negative direction of the Z axis) and front surface (surface facing the positive direction of the Z axis). The conductive pattern 31 includes a circuit pattern 31a and a ground pattern 31b.

[0027] The circuit pattern 31a is a conductive pattern to which, for example, a signal line 45a of a coaxial cable 45 extending from an amplifier board (not shown) is connected. In addition, 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 portion of the base 11 so as to support the main body of the patch antenna 30. The ground pattern 31b is grounded by being electrically connected to the pedestal portions 11a. Note that a metallic shield cover 50, for example, is attached to the back surface of the circuit board 32 to protect the circuit pattern 31a.

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

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

[0031] The radiating element 35 is a substantially quadrilateral conductive element having an area smaller than the front surface of the first dielectric member 34, and is formed on the front surface of the first 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.

[0032] Here, "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. Furthermore, the "approximately quadrilateral" shape may have a notch (recess) 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 the desired frequency band.

[0033] The second dielectric member 36 is a dielectric member provided around the first dielectric member 34. Similar to the first dielectric member 34, the front and back surfaces of the second dielectric member 36 are parallel to the X-axis and Y-axis, with the front surface of the second dielectric member 36 facing in the positive direction of the Z-axis and the back surface of the second dielectric member 36 facing in the negative direction of the Z-axis. Similar to the first dielectric member 34, the back surface of the second dielectric member 36 is attached to the conductive pattern 33 with, for example, double-sided tape.

[0034] As shown in FIGS. 3 to 6, in this embodiment, the second dielectric member 36 is formed in a shape that surrounds the periphery of the first dielectric member 34. Furthermore, the second dielectric member 36 is in contact with the outer edge (here, sides 34a to 34d) of the first dielectric member 34. Here, "the periphery of the first dielectric member 34" also includes a range away from the outer edge of the first dielectric member 34. Therefore, in FIGS. 3 to 6, the second dielectric member 36 is formed in a shape that surrounds the periphery of the first dielectric member 34 while being in contact with the outer edge of the first dielectric member 34. However, the second dielectric member 36 may be formed in a shape that surrounds at least a portion of the periphery of the first dielectric member 34 while being spaced outward from the outer edge of the first dielectric member 34. Note that the outside of the first dielectric member 34 refers to the direction away from the center point 35p of the radiating element 35 formed on the first dielectric member 34 on the base 11. Furthermore, the shape of the outer edge of the second dielectric member 36 is substantially quadrilateral. However, as will be described later, the number, shape and installation manner of the second dielectric members 36 are not limited to those shown in FIGS.

[0035] The second dielectric member 36 is made of a dielectric material such as ceramic. The second dielectric member 36 may be made of the same dielectric material as the first dielectric member 34, or may be made of a dielectric material different from that of the first dielectric member 34.

[0036] The through hole 41 penetrates the circuit board 32, the conductive pattern 33, and the first dielectric member 34. A feeder line 42 that connects the circuit pattern 31a and the radiating element 35 is provided inside the through hole 41. The feeder line 42 connects the circuit pattern 31a and the radiating element 35 while being electrically insulated from the conductive pattern 33, which is grounded. In this embodiment, the point where the feeder line 42 is electrically connected to the radiating element 35 is defined as a feed point 43a.

[0037] 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 to this, and for example, as shown by the dashed 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.

[0038] The "center point 35p of the radiating element 35" refers to the center point of the outer edge of the radiating element 35, i.e., the geometric center. The single-feed type radiating element 35 of FIG. 5 has, for example, a substantially rectangular shape with different vertical and horizontal lengths so that it can transmit and receive the desired circularly polarized waves. Note that a "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.

[0039] 3 to 5, the configuration has been described in which only one feeder line, the feeder line 42, is connected to the radiating element 35, but two feeders may be provided by adding one feeder line connected to the radiating element 35. The additional feeder line can be provided via a through-hole (not shown) that penetrates the first dielectric member 34, etc., similar to the feeder line 42, and therefore a detailed description of the configuration will be omitted here.

[0040] Fig. 6 is a diagram showing the positions of the feed points 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 just 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 waves. Furthermore, the radiating element 35 in Fig. 6 has, for example, an approximately square shape with equal length and width so that it can transmit and receive the desired circularly polarized waves. Note that "approximately square" is a shape that falls within the "approximately quadrilateral" mentioned above.

[0041] ==Comparative Example== 7 is a plan view of a patch antenna 30X of a comparative example. The patch antenna 30X is an antenna in which the second dielectric member 36 is not provided in the patch antenna 30. The patch antenna 30X has the same configuration as the patch antenna 30 of the above-described embodiment, except that the second dielectric member 36 is not provided. For example, the patch antenna 30X is configured to include a circuit board 32, a first dielectric member 34, a radiating element 35, and a shield cover 50.

[0042] ==Electric field distribution of patch antenna== The upper part of FIG. 8 shows the electric field distribution when the patch antenna 30X of the comparative example is used, as viewed from the side. The lower part of FIG. 8 shows the electric field distribution when the patch antenna 30 of this embodiment is used, as viewed from the side. As shown in FIG. 8, in the patch antenna 30X of the comparative example, the electric field extends only to approximately the upper side of the radiating element 35, whereas in the patch antenna 30 of this embodiment, the electric field extends to the lower side of the radiating element 35. This shows that the patch antenna 30 of this embodiment has stronger radiation of radio waves at low elevation angles than the patch antenna 30X of the comparative example. Therefore, in the patch antenna 30 of this embodiment, the second dielectric member 36 is provided around the first dielectric member 34, thereby providing the function of strengthening radiation of radio waves at low elevation angles.

[0043] <<<Installation conditions for the second dielectric member>>> As described above, the second dielectric member 36 functions to enhance radiation of radio waves at low elevation angles, and the radiating element 35 receives left-handed circularly polarized waves in the 2.3 GHz band. Therefore, changing the installation mode and size of the second dielectric member 36 affects the radio waves received by the radiating element 35. For this reason, first, the installation conditions of the second dielectric member 36 will be described with reference to Figures 4 and 6. In Figure 6, the rotation direction of the left-handed circularly polarized waves received by the radiating element 35 is indicated by arrow A.

[0044] ==Regarding the relative permittivity of the second dielectric material== In this embodiment, the second dielectric member 36 has a dielectric constant ε r1 Relative permittivity ε greater than r2 The dielectric material is r2 >ε r1 Specifically, the first dielectric member 34 has a relative dielectric constant ε r1 A dielectric material having a relative dielectric constant ε of 7.82 is used as the second dielectric member 36. r2 However, as will be described later, the second dielectric member 36 is made of a dielectric material having a relative dielectric constant ε r1 The relative permittivity ε r2 A dielectric material of ε r2 ≦ε r1 ).

[0045] ==Width of the second dielectric member== As shown in FIG. 6 , the second dielectric member 36 is provided so as to surround the periphery of the first dielectric member 34. Here, the "width W" of the second dielectric member 36 is the size of the second dielectric member 36 in a direction perpendicular to the outer edges (here, sides 34a to 34d) of the first dielectric member 34 in a plan view of the front surface of the radiating element 35 seen from the positive direction of the Z axis. In other words, the width W is the distance between the outer edge of the second dielectric member 36 corresponding to the outer edge of the first dielectric member 34 and the outer edge of the first dielectric member 34. In this embodiment, the width W of the second dielectric member 36 is the same all around, but this is not limited to this. For example, the widths W of the second dielectric members 36 facing each side of the first dielectric member 34 may be different from each other. Furthermore, some of the widths W of the second dielectric members 36 facing each side of the first dielectric member 34 may be the same. Furthermore, although the respective sides of the outer edge of the second dielectric member 36 facing the respective sides of the first dielectric member 34 are parallel to each other, this is not limitative. For example, the width W may be shaped to increase or decrease in a stepwise or gradual manner.

[0046] ==Thickness of the second dielectric member== The "thickness T" refers to, for example, the size of an object in the vertical direction (Z direction). For example, in FIG. 4, the size of the second dielectric member 36 in the vertical direction (Z direction) is defined as the "thickness T" of the second dielectric member 36. In this embodiment, the second dielectric member 36 is formed so that the thickness T of the second dielectric member 36 is equal to the thickness T of the first dielectric member 34.

[0047] ==Simulation condition 1== Here, the size of the radiating element 35, the relative dielectric constant ε of the first dielectric member 34, r1 and size, relative dielectric constant ε of the second dielectric member 36 r2 The gains of the patch antenna 30 and the comparative patch antenna 30X were calculated under predetermined conditions (hereinafter referred to as "simulation conditions 1"), such as the size of the base 11, the size of the circuit board 32, and the power supply method. For convenience, the simulation of the patch antenna 30 and the patch antenna 30X uses a model that omits the circuit pattern 31a and the like, which have little effect on the gain.

[0048] 9 is a diagram showing the relationship between the elevation angle and the average gain of the patch antenna 30X of the comparative example. r2 9A and 9B are diagrams showing the relationship between elevation angle and average gain at elevation angles of 20°, 25°, and 30°, respectively. In these diagrams, the horizontal axis represents elevation angle, and the vertical axis represents average gain. As shown in FIG. 9A, the average gains of the patch antenna 30X of the comparative example at elevation angles of 20°, 25°, and 30° are −1.2 dBic, 0.1 dBic, and 1.2 dBic. In contrast, as shown in FIG. 10A, the average gains of the patch antenna 30 of this embodiment at elevation angles of 20°, 25°, and 30° are −0.5 dBic, 0.6 dBic, and 1.6 dBic. Therefore, the patch antenna 30 of this embodiment has a higher average gain at low elevation angles of 20° to 30° than the patch antenna 30X of the comparative example.

[0049] In this way, by providing the second dielectric member 36 around the first dielectric member 34, the gain of the patch antenna 30 at low elevation angles is improved, and as a result, the patch antenna 30 can efficiently receive radio waves arriving at low elevation angles.

[0050] <<<Changes in installation conditions for the second dielectric member>>> Here, a description will be given of a case where the installation conditions for the second dielectric member 36 are changed. Two or more of the conditions described below may be changed and applied in combination.

[0051] ==relative permittivity ε r2 If you change == First, among the installation conditions of the second dielectric member 36, the relative dielectric constant ε r2 The characteristics of the patch antenna 30 are examined when the relative dielectric constant ε r2 Various conditions of the patch antenna 30 other than the above (for example, the physical size of the main part of the patch antenna 30, the power feeding method, the relative dielectric constant ε of the first dielectric member 34, r1 ) etc. are the same as those in Simulation Condition 1 described above.

[0052] Here, the relative permittivity ε r2 When the second dielectric member 36 having a diameter of 30 is used (ε r2 >ε r1 ), relative permittivity ε r2 When the second dielectric member 36 having a diameter of 40 is used (ε r2 >ε r1 ), relative permittivity ε r2 When the second dielectric member 36 having a value of 2 is used (ε r2 <ε r1 ), relative permittivity ε r2 When the second dielectric member 36 having a diameter of 7.82 is used (ε r2 =ε r1 ), and the results are shown in Figs. 11 to 14. Fig. 11 shows the results of changing the patch antenna 30 (ε r2 12 is a diagram showing the relationship between the elevation angle and the average gain of the patch antenna 30 (ε r2 13 is a graph showing the relationship between the elevation angle and the average gain of the patch antenna 30 (ε r214 is a graph showing the relationship between the elevation angle and the average gain of the patch antenna 30 (ε r2 1. The horizontal axis represents the elevation angle and the vertical axis represents the average gain. r2 The solid line shows the results when the relative permittivity ε r2 The results for the case where the second dielectric member 36 (=20) was used (FIG. 10) are indicated by a dashed line, and the results for the patch antenna 30X of the comparative example (FIG. 9) are indicated by a broken line for comparison.

[0053] Relative permittivity ε r2 The patch antenna 30 using the second dielectric member 36 having a relative dielectric constant ε r2 As in the case where the second dielectric member 36 having a relative dielectric constant ε of 20 is used, the average gain at a low elevation angle of 20° to 30° is higher than that of the patch antenna 30X of the comparative example. r2 In the patch antenna 30 using the second dielectric member 36 having the dielectric constant ε 30, the average gains at the elevation angles of 20°, 25°, and 30° are −0.4 dBic, 0.8 dBic, and 1.7 dBic. r2 In the patch antenna 30 using the second dielectric member 36 with a dielectric constant of 40, the average gains at elevation angles of 20°, 25°, and 30° are 0.0 dBic, 1.1 dBic, and 2.0 dBic. r2 The second dielectric member 36 has a relative dielectric constant ε r2 The patch antenna 30 using the second dielectric member 36 with a relative dielectric constant ε r2 The effect of improving the average gain at low elevation angles of 20° to 30° is greater than when the second dielectric member 36 of 20° is used.

[0054] In the above description, the relative dielectric constant ε of the second dielectric member 36 r2 is the relative dielectric constant ε of the first dielectric member 34 r1 If it is greater than (ε r2 >ε r1 ) was examined, and as shown in FIGS. 13 and 14, the relative dielectric constant ε r2is the relative dielectric constant ε of the first dielectric member 34 r1 In the following case (ε r2 ≦ε r1 ), the average gain at a low elevation angle of 20° to 30° is higher than that of the patch antenna 30X of the comparative example. However, the relative dielectric constant ε r2 is the relative dielectric constant ε of the first dielectric member 34 r1 The relative dielectric constant ε of the second dielectric member 36 is r2 is the relative dielectric constant ε of the first dielectric member 34 r1 10 to 14, the effect of improving the average gain at low elevation angles is greater when the relative dielectric constant ε r2 The larger the value, the greater the effect of improving the average gain at low elevation angles.

[0055] Therefore, in order for the second dielectric member 36 to contribute to improving the gain at low elevation angles, the relative dielectric constant ε r2 is the relative dielectric constant ε of the first dielectric member 34. r1 In this case, the relative dielectric constant ε of the second dielectric member 36 is preferably larger than r2 is preferably 30 or more, and more preferably 35 or more. r2 It is more preferable to set the value to 40 or more.

[0056] ==When thickness T is changed== In the patch antenna 30 under simulation condition 1, the thickness T of the first dielectric member 34 is 6 mm, and the thickness T of the second dielectric member 36 is also 6 mm. That is, the thickness T of the first dielectric member 34 and the thickness T of the second dielectric member 36 are the same. However, the thickness T of the second dielectric member 36 may be changed.

[0057] Here, assuming that the thickness T of the second dielectric member 36 is smaller than the thickness T of the first dielectric member 34, the results of varying the thickness T of the second dielectric member 36 to 5 mm and 3 mm are shown in FIGS. 15 and 16, respectively. Also, assuming that the thickness T of the second dielectric member 36 is larger than the thickness T of the first dielectric member 34, the results of varying the thickness T of the second dielectric member 36 to 7 mm and 8 mm are shown in FIGS. 17 and 18, respectively. Note that FIGS. 15 to 18 show the results of varying the relative dielectric constant ε r2 15 to 18, these results are shown by solid lines, and the thickness T is 6 mm and the relative dielectric constant ε r2 The results when the second dielectric member 36 having a diameter of 40 was used (FIG. 12) are shown by a dashed line, and the results of the comparative patch antenna 30X (FIG. 9) are shown by a broken line for comparison.

[0058] Similar to the patch antenna 30 in which the thickness T of the second dielectric member 36 is set to 6 mm, the patch antenna 30 (FIGS. 15 and 16) in which the thickness T of the second dielectric member 36 is set to 5 mm or 3 mm has a higher average gain at low elevation angles of 20° to 30° than the patch antenna 30X (FIG. 9). Therefore, it can be seen that even when the thickness T of the second dielectric member 36 is smaller than the thickness T of the first dielectric member 34, the average gain at low elevation angles of 20° to 30° is higher than that of the patch antenna 30X.

[0059] Similarly to the patch antenna 30 in which the thickness T of the second dielectric member 36 is set to 6 mm, the patch antenna 30 (FIGS. 17 and 18) in which the thickness T of the second dielectric member 36 is set to 7 mm or 8 mm also has a higher average gain at low elevation angles of 20° to 30° than the patch antenna 30X (FIG. 9). Therefore, even when the thickness T of the second dielectric member 36 is greater than the thickness T of the first dielectric member 34, the average gain at low elevation angles of 20° to 30° is higher than that of the patch antenna 30X. However, compared to the patch antenna 30 (FIG. 12) in which the thickness T of the second dielectric member 36 is set to 6 mm, there is no significant improvement in the average gain at low elevation angles of 20° to 30°. Moreover, each increase in the thickness T of the second dielectric member 36 increases the manufacturing cost of the dielectric member itself and makes it difficult to miniaturize the antenna device and patch antenna.

[0060] Therefore, in order to reduce manufacturing costs, miniaturize the antenna device and patch antenna, and further improve the gain at low elevation angles, it is preferable that the thickness T of the second dielectric member 36 be approximately the same as or smaller than the thickness T of the first dielectric member 34.

[0061] ==When a plurality of second dielectric members 36 are provided around the first dielectric member 34== In the above, the patch antenna 30 in which one second dielectric member 36 is formed to surround the first dielectric member 34 has been examined, but this is not limiting. A plurality of second dielectric members may be provided around the first dielectric member 34.

[0062] Fig. 19 is a plan view of the patch antenna 30A. As shown in Fig. 19, in the patch antenna 30A, four second dielectric members 37 to 40 are provided around the first dielectric member 34. The radio waves received by the radiating element 35 are affected by changing the installation manner and size of the second dielectric members 37 to 40. Therefore, the installation conditions of the second dielectric members 37 to 40 will be described with reference to Fig. 19.

[0063] ==Width of the second dielectric member== Among the second dielectric members 37-40, for example, the "width W" of the second dielectric member 39 is the size of the second dielectric member 36 in a direction perpendicular to the outer edge (here, side 34c) of the first dielectric member 34 in a plan view of the front surface of the radiating element 35 seen from the positive direction of the Z axis, similar to the patch antenna 30 shown in FIG. 6 . In other words, the width W is the distance between the outer edge of the second dielectric member 36 corresponding to the outer edge of the first dielectric member 34 and the outer edge of the first dielectric member 34. The "width W" of the second dielectric members other than the second dielectric member 39 is also defined in the same way. In this embodiment, the widths W of the second dielectric members 37-40 are all the same, but this is not limited to this. For example, the widths W of the second dielectric members 37-40 facing each side of the first dielectric member 34 may be different from each other. Furthermore, some of the widths W of the second dielectric members 37-40 facing each side of the first dielectric member 34 may be the same. Furthermore, although the respective sides of the outer edge of the second dielectric member 36 facing the respective sides of the first dielectric member 34 are parallel to each other, this is not limitative. For example, the width W may be shaped to increase or decrease in a stepwise or gradual manner.

[0064] ==Length D of the second dielectric member== Among the second dielectric members 37 to 40, for example, the "length D" of the second dielectric member 38 is the size of the second dielectric member 36 in a direction parallel to the outer edge (here, side 34b) of the first dielectric member 34 in a plan view of the front surface of the radiating element 35 seen from the positive direction of the Z axis. In other words, the length D is the distance from one end of the outer edge of the first dielectric member 34 to the closest end in a straight line. The "length D" of the second dielectric members other than the second dielectric member 38 is also defined in a similar manner. In the present embodiment, the lengths D of the second dielectric members 37 to 40 are all the same, but this is not limited thereto. For example, the lengths D of the second dielectric members 37 to 40 facing each side of the first dielectric member 34 may be different from one another. Furthermore, some of the lengths D of the second dielectric members 37 to 40 facing each side of the first dielectric member 34 may be the same. Furthermore, although the second dielectric members 37 to 40 are each substantially rectangular in shape, this is not limited thereto. For example, the second dielectric members 37 to 40 may have a quadrilateral shape such as a square, a parallelogram, or a trapezoid, or may have a triangular shape.

[0065] ==Gap G with the first dielectric member 34== As shown in FIG. 32, among the second dielectric members 37-40, for example, the "gap G" between the second dielectric member 37 and the first dielectric member 34 is the distance between the side of the second dielectric member 37 closest to the first dielectric member 34 and the outer edge (here, side 34a) of the first dielectric member 34 facing the second dielectric member 37 in a plan view of the front surface of the radiating element 35 seen from the positive direction of the Z axis. The "gap G" of the second dielectric members other than the second dielectric member 37 is also defined in the same way. As shown in FIG. 19, the second dielectric members 37-40 are in contact with the outer edge (here, sides 34a-34d) of the first dielectric member 34. Therefore, the gaps G between the second dielectric members 37-40 and the first dielectric member 34 are all 0 mm.

[0066] == Position and offset amount OS of the second dielectric member == 34, for each of the second dielectric members 38 and 40, the distance shifted along the X-axis direction from the position of the midpoint of the side 34b (or side 34d) of the first dielectric member 34 in the X-axis direction is defined as the offset amount OS in the X-axis direction. Also, for each of the second dielectric members 37 and 39, the distance shifted along the Y-axis direction from the position of the midpoint of the side 34a (or side 34c) of the first dielectric member 34 in the Y-axis direction is defined as the offset amount OS in the Y-axis direction.

[0067] 19, the offset amount OS in the X-axis direction of the midpoints of the second dielectric members 38, 40 in the X-axis direction is 0 mm. That is, the positions of the midpoints of the second dielectric members 38, 40 in the X-axis direction are aligned with the position of the midpoint of the side 34b (or side 34d) of the first dielectric member 34 in the X-axis direction.

[0068] 19, the offset amount OS in the Y-axis direction of the midpoints of the second dielectric members 37 and 39 in the Y-axis direction is 0 mm. That is, the positions of the midpoints of the second dielectric members 37 and 39 in the Y-axis direction are aligned with the midpoint of the side 34a (or side 34c) of the first dielectric member 34 in the Y-axis direction.

[0069] == Regarding the placement of the second dielectric member == Each of the second dielectric members 37 to 40 is disposed parallel to the outer edge of the first dielectric member 34. Specifically, the second dielectric member 37 is disposed parallel to the side 34a of the first dielectric member 34, the second dielectric member 38 is disposed parallel to the side 34b of the first dielectric member 34, the second dielectric member 39 is disposed parallel to the side 34c of the first dielectric member 34, and the second dielectric member 40 is disposed parallel to the side 34d of the first dielectric member 34. Here, when, for example, the second dielectric member 40 among the second dielectric members 37 to 40 is "parallel" to the side 34d of the first dielectric member 34, this means that the side of the second dielectric member 40 closest to the first dielectric member 34 is parallel to the outer edge (here, the side 34d) of the first dielectric member 34 facing the second dielectric member 40. The same applies to the definition of parallelism between second dielectric members and the outer edge of the first dielectric member 34 other than the second dielectric member 40. Furthermore, although the second dielectric members 37 to 40 have been described as having a substantially rectangular shape, the shape is not limited to this. For example, the second dielectric members 37 to 40 may have a quadrilateral shape such as a square, parallelogram, or trapezoid, or may have a triangular shape.

[0070] ==Simulation condition 2== Below, the gains of the patch antenna 30A and the comparative patch antenna 30X were calculated under predetermined conditions (hereinafter referred to as "simulation condition 2"), such as the width W, length D, gap G, and offset amount OS of each of the second dielectric members 37 to 40. Note that the various conditions of the patch antenna 30A other than simulation condition 2 are the same as those of the patch antenna 30 described above under simulation condition 1.

[0071] Fig. 20 is a diagram showing the relationship between elevation angle and average gain in patch antenna 30A. In this diagram, the horizontal axis represents elevation angle, and the vertical axis represents average gain. In Fig. 20, the results are shown by a solid line, the results of patch antenna 30 (Fig. 12) formed in a shape where a single second dielectric member 36 surrounds first dielectric member 34 are shown by a dashed-dotted line, and the results of comparative patch antenna 30X (Fig. 9) are shown by a dashed line for comparison.

[0072] Like the patch antenna 30, the patch antenna 30A also has a higher average gain at low elevation angles of 20° to 30° than the patch antenna 30X. Therefore, even when four second dielectric members 37 to 40 are provided and each of the second dielectric members 37 to 40 is arranged parallel to the outer edge of the first dielectric member 34, it can be seen that the average gain at low elevation angles of 20° to 30° is higher than that of the patch antenna 30X. As a result, the patch antenna 30A can also efficiently receive incoming radio waves at low elevation angles.

[0073] <<<Changes in installation conditions for the second dielectric member>>> Here, a description will be given of a case where the installation conditions of the second dielectric members 37 to 40 are changed. Two or more of the conditions described below may be changed and applied in combination.

[0074] ==When the number of second dielectric members is changed== In the above-described patch antenna 30A, four second dielectric members 37 to 40 are provided around the first dielectric member 34. However, the number of second dielectric members provided around the first dielectric member 34 may be changed.

[0075] Fig. 21 is a plan view of a patch antenna 30B. The patch antenna 30B is an antenna obtained by removing the second dielectric members 37 and 39 from the patch antenna 30A shown in Fig. 19 and providing only two second dielectric members 38 and 40. In the patch antenna 30B, each of the second dielectric members 38 and 40 is provided parallel to the outer edge of the first dielectric member 34 (here, side 34b or side 34d).

[0076] Fig. 22 shows the relationship between elevation angle and average gain for patch antenna 30B. In this figure, the horizontal axis represents elevation angle, and the vertical axis represents average gain. In Fig. 22, the results are shown by a solid line, the results for patch antenna 30A (Fig. 20) are shown by a dashed-dotted line, and the results for comparative patch antenna 30X (Fig. 9) are shown by a dashed line for comparison.

[0077] Like the patch antenna 30A, the patch antenna 30B also has a higher average gain at low elevation angles of 20° to 30° than the patch antenna 30X. Therefore, not only when four second dielectric members 37 to 40 are provided, but also when two second dielectric members 38, 40 are provided parallel to the outer edge of the first dielectric member 34, it can be seen that the average gain at low elevation angles of 20° to 30° is higher than that of the patch antenna 30X. As a result, the patch antenna 30B can also efficiently receive incoming radio waves at low elevation angles.

[0078] The positions of the two second dielectric members are not limited to those shown in FIG. 21 . For example, the two second dielectric members 37, 49 may be arranged parallel to the side 34a or the side 34c, respectively. Alternatively, the two second dielectric members 37, 49 may be arranged parallel to the adjacent sides 34a, 34b. Furthermore, a plurality of second dielectric members 37-40 other than those described above may be arranged around the first dielectric member 34 to increase the average gain at low elevation angles of 20° to 30°. Although the second dielectric members 37-40 have been described as having a substantially rectangular shape, this is not limiting. For example, the second dielectric members 37-40 may have a quadrilateral shape such as a square, parallelogram, or trapezoid, or may have a triangular shape.

[0079] Although the patch antennas 30, 30A, and 30B described above are designed to receive left-handed circularly polarized waves, they may also be designed to receive linearly polarized waves. In such cases, a single-feed system is employed, and the feed point 41a is offset from the center point of the radiating element 35 in the positive direction of the X-axis. The primary polarization plane is a plane defined by the center point of the radiating element 35, a line connecting the feed point, and the normal to the radiating element 35. Therefore, the primary polarization plane is parallel to the XZ plane. The secondary polarization plane is a plane that is orthogonal to the primary polarization plane and passes through the center point of the radiating element 35. Therefore, the cross polarization plane is parallel to the YZ plane.

[0080] The patch antenna 30B may be configured to receive the linearly polarized wave described above. In this case, the second dielectric members 38 and 40 are disposed opposite each other across the radiating element 35 in the direction of a line connecting the feed point 43a of the radiating element 35 and the center point 35P of the shape of the radiating element 35. When the patch antenna 30B receives linearly polarized wave, the main polarization plane is the XZ plane, and the second dielectric members 38 and 40 intersect with the main polarization plane. Although detailed calculation results are omitted here, even in such a case, the gain at low elevation angles can be improved, as in FIG. 22.

[0081] In the above, a case where a plurality of second dielectric members 36 are provided around the first dielectric member 34 has been verified, but this is not limitative. A single second dielectric member may be provided around a portion of the periphery of the first dielectric member 34.

[0082] Fig. 23 is a plan view of a patch antenna 30C. The patch antenna 30C is an antenna obtained by eliminating the second dielectric members 37, 39, and 40 from the patch antenna 30A shown in Fig. 19 and providing only a single second dielectric member 38. In the patch antenna 30C, the second dielectric member 38 is provided parallel to the outer edge (here, side 34b) of the first dielectric member 34.

[0083] Fig. 24 shows the relationship between elevation angle and average gain for patch antenna 30C. In this figure, the horizontal axis represents elevation angle, and the vertical axis represents average gain. In Fig. 24, the results are shown by a solid line, the results for patch antenna 30A (Fig. 20) are shown by a dashed-dotted line, and the results for comparative patch antenna 30X (Fig. 9) are shown by a dashed line for comparison.

[0084] Like patch antenna 30A, patch antenna 30C has a higher average gain at low elevation angles of 20° to 30° than patch antenna 30X. Therefore, it can be seen that not only when a plurality of second dielectric members 37 to 40 are provided, but also when one second dielectric member 38 is provided parallel to the outer edge of first dielectric member 34, patch antenna 30C has a higher average gain at low elevation angles of 20° to 30° than patch antenna 30X.

[0085] The arrangement position of one second dielectric member is not limited to the case shown in Fig. 23. For example, one second dielectric member 37 may be provided parallel to the side 34a. Furthermore, although the second dielectric members 37 to 40 have been described as having a substantially rectangular shape, this is not limiting. For example, the second dielectric members 37 to 40 may have a quadrilateral shape such as a square, parallelogram, or trapezoid, or may have a triangular shape.

[0086] ==When width W is changed== Here, Figures 25 to 28 show the results of changing the width W of patch antenna 30A under simulation condition 2 to 1 mm, 4 mm, 8 mm, and 10 mm. Figures 25 to 28 are diagrams showing the relationship between the elevation angle and the average gain. In these figures, the horizontal axis represents the elevation angle, and the vertical axis represents the average gain. In Figures 25 to 28, these results are shown by solid lines, and for comparison, the results of patch antenna 30A in which four second dielectric members 37 to 40 are provided around the first dielectric member 34 (Figure 20) are shown by dashed-dotted lines, and the results of patch antenna 30X (Figure 9) are shown by dashed lines.

[0087] As with patch antenna 30 and patch antenna 30A, even when the width W is changed, the average gain at a low elevation angle of 20° to 30° is higher than that of patch antenna 30X. Therefore, it can be seen that the average gain at a low elevation angle of 20° to 30° is higher than that of patch antenna 30X, not limited to when the width W of each of second dielectric members 37 to 40 is 6 mm.

[0088] ==When length D is changed== Here, Figures 29 to 31 show the results of changing the length D from 15 mm, 10 mm, and 5 mm under simulation condition 2 for patch antenna 30A. Figures 29 to 31 are diagrams showing the relationship between the elevation angle and the average gain. In these figures, the horizontal axis represents the elevation angle, and the vertical axis represents the average gain. In Figures 29 to 31, these results are shown by solid lines, and for comparison, the results for patch antenna 30A in which four second dielectric members 37 to 40 are provided around the first dielectric member 34 (Figure 20) are shown by dashed-dotted lines, and the results for patch antenna 30X (Figure 9) are shown by dashed lines.

[0089] As with patch antenna 30 and patch antenna 30A, even when the length D is changed, the average gain at a low elevation angle of 20° to 30° is higher than that of patch antenna 30X. Therefore, it can be seen that the average gain at a low elevation angle of 20° to 30° is higher than that of patch antenna 30X, not limited to when the length D of each of second dielectric members 37 to 40 is 28 mm.

[0090] ==When gap G is changed== In the above description, the second dielectric members 37 to 40 are in contact with the outer edge of the first dielectric member 34. However, the second dielectric members 37 to 40 may be provided spaced apart from the outer edge of the first dielectric member 34.

[0091] 32 is a plan view of the patch antenna 30D. The patch antenna 30D includes four second dielectric members 37-40, each of which is arranged parallel to the outer edge of the first dielectric member 34 (sides 34a-34d in this example). The second dielectric members 37-40 are spaced apart from the outer edge of the first dielectric member 34 to the outside. The gap G between the second dielectric members 37-40 and the first dielectric member 34 is 0.5 mm.

[0092] Figure 33 shows the relationship between elevation angle and average gain for patch antenna 30D. In this figure, the horizontal axis represents elevation angle, and the vertical axis represents average gain. In Figure 33, the results are shown by a solid line, with the results for patch antenna 30A (Figure 20) represented by a dashed-dotted line and the results for patch antenna 30X (Figure 9) represented by a dashed line for comparison.

[0093] Similar to patch antenna 30A, patch antenna 30D also has a higher average gain at low elevation angles of 20° to 30° than patch antenna 30X. Therefore, even when gap G is provided, it can be seen that patch antenna 30D has a higher average gain at low elevation angles of 20° to 30° than patch antenna 30X.

[0094] In the above description, the case where the gap G is changed in the patch antenna 30A in which four second dielectric members 37-40 are provided around the first dielectric member 34 has been examined, but this is not limiting. Regarding the patch antenna 30 (FIG. 6) in which one second dielectric member 36 is formed in a shape surrounding the first dielectric member 34, when the gap G is changed, detailed calculation results are omitted, but similar to FIG. 33, it is possible to improve the gain at low elevation angles. Furthermore, the second dielectric members 37-40 may be arranged so as to form an angle with respect to the outer edge of the first dielectric member 34. At least one of the second dielectric members 37-40 may be arranged so as to form an angle with respect to the outer edge of the first dielectric member 34. Furthermore, the shape of the second dielectric members 37-40 may be a quadrilateral, such as a square, parallelogram, or trapezoid, or may be a triangle.

[0095] ==When the offset amount OS is changed== As shown in FIG. 19, in the patch antenna 30A, the offset amount OS in the X-axis direction and the offset amount OS in the Y-axis direction are both 0 mm, but these may be changed.

[0096] For example, Figure 34 is a plan view of an example of a patch antenna 30E in which the offset amount OS is changed. Here, the position of the midpoint of the second dielectric members 38 and 40 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 34b and 34d of the first dielectric member 34 in the X-axis direction. Furthermore, the position of the midpoint of the second dielectric members 37 and 39 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 34a and 34c of the first dielectric member 34 in the Y-axis direction. Figure 35 is a diagram showing the relationship between the elevation angle and the average gain when the length D is 15 mm and the offset amounts in the X-axis and Y-axis directions are 6.5 mm. In this diagram, the horizontal axis represents the elevation angle, and the vertical axis represents the average gain. In FIG. 35, this result is shown by a solid line, the result of patch antenna 30A (D=15) with no offset (FIG. 29) is shown by a dashed line, and the result of patch antenna 30X (FIG. 9) is shown by a dashed line for comparison.

[0097] As is clear from FIG. 35, the patch antenna 30E, like the patch antenna 30A without offset, can increase the gain at low elevation angles more than the patch antenna 30X.

[0098] The position of the midpoint of the second dielectric members 38 and 40 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 34b and 34d of the first dielectric member 34 in the X-axis direction. The position of the midpoint of the second dielectric members 37 and 39 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 34a and 34c of the first dielectric member 34 in the Y-axis direction. Detailed calculation results are omitted here, but even in such a case, the gain at low elevation angles can be improved, as in FIG. 35. The shape of the second dielectric members 37 to 40 may be a quadrilateral, such as a square, parallelogram, or trapezoid, or a triangle.

[0099] Incidentally, even when an offset amount OS is set, as in the case of patch antenna 30E, it is possible to improve the gain at low elevation angles, but the second dielectric members 37-40 may extend outside the range of each of the sides 34a-34d of the first dielectric member 34. For this reason, with such a configuration, the size of patch antenna 30E increases. Therefore, it is preferable to set the offset amount OS so that each of the second dielectric members 37-40 falls within the range of each of the sides 34a-34d. Setting the offset amount OS in this way allows the space required for the patch antenna to be reduced.

[0100] ==Shape of the radiating element== In the patch antenna 30, the radiating element 35 and the first dielectric member 34 are "approximately quadrilateral," but are not limited to this and may be, for example, circular, elliptical, or a polygon other than a substantially quadrilateral. If the radiating element 35 or the first dielectric member 34 is, for example, circular, the second dielectric member 36 may have an arc shape that follows the outer edge of the radiating element 35 or the first dielectric member 34. Even when such a radiating element or second dielectric member is used, it is possible to improve the gain at low elevation angles.

[0101] Although the patch antenna 30 of this embodiment is provided in the in-vehicle 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 typical shark fin antenna. The patch antenna 30 may also be provided in an antenna device mounted on an instrument panel. In such a case, the patch antenna 30 may be directly provided on a metal plate or the like corresponding to the base 11.

[0102] <<<<Summary>>>> The patch antenna 30 of this embodiment has been described above. For example, as shown in FIGS. 3, 5, 6, 19, 21, 23, 32, and 34, in the patch antennas 30A to 30E, at least one of the second dielectric members 36 to 40 is provided around the first dielectric member 34, that is, outside the outer edge of the first dielectric member 34. Therefore, by using such patch antennas 30A to 30E, it is possible to improve the gain at low elevation angles. Furthermore, with such a configuration, even if the area of ​​the ground is small, it is possible to improve the gain at low elevation angles, and the miniaturization of the antenna device and patch antenna is not hindered.

[0103] Furthermore, the relative dielectric constant ε of the second dielectric member 36 r2 is the relative dielectric constant ε of the first dielectric member 34 r1 The following is also acceptable (ε r2 ≦ε r1 ), the relative dielectric constant ε of the second dielectric member 36 r2 is the relative dielectric constant ε of the first dielectric member 34 r1 It is desirable that it is larger than (ε r2 >ε r1 ). Such a relative permittivity ε r2 By providing the second dielectric member 36, it is possible to reliably improve the gain at low elevation angles.

[0104] Furthermore, the relative dielectric constant ε of the second dielectric member 36 r2 is preferably 30 or more (ε r2 ≧30). Such a relative permittivity ε r2 By providing the second dielectric member 36, the gain at low elevation angles can be further improved.

[0105] Furthermore, it is desirable that the thickness T of the second dielectric member 36 be approximately the same as or smaller than the thickness T of the first dielectric member 34. By providing the second dielectric member 36 with such a thickness T, it is possible to reduce the size of the antenna device and the patch antenna while suppressing the manufacturing costs.

[0106] Furthermore, as described above, the patch antennas 30A to 30E can improve the gain at low elevation angles even when the radiating element 35 receives circularly polarized waves.

[0107] Furthermore, when the radiating element 35 receives circularly polarized waves as described above, the patch antenna 30 is formed in a shape that surrounds the first dielectric member 34, as shown in Figures 3, 5 and 6. In this way, even when the radiating element 35 receives circularly polarized waves, the gain at low elevation angles can be improved.

[0108] Furthermore, when the radiating element 35 receives circularly polarized waves as described above, the patch antenna 30 may not only be formed in a shape surrounding the first dielectric member 34, but also, for example, as in the patch antenna 30A shown in Fig. 19, a plurality of second dielectric members 37-40 may be provided, and each of the plurality of second dielectric members 37-40 may be provided parallel to the outer edge of the first dielectric member 34. In this way, even when the radiating element 35 receives circularly polarized waves, the gain at low elevation angles can be improved.

[0109] Furthermore, the patch antenna 30 can improve the gain at low elevation angles not only when receiving circularly polarized waves but also when receiving linearly polarized waves. For example, as shown in Fig. 21, a patch antenna 30B has a plurality of second dielectric members 38, 40 arranged along the main polarization plane of the radiating element 35 and facing each other with the radiating element 35 in between. By arranging the second dielectric members 38, 40 in such positions, the gain at low elevation angles can be improved.

[0110] 3, 5, 6, 19, 21, 23, and 34, the second dielectric members 36 to 40 of the patch antennas 30, 30A, 30B, 30C, and 30E are in contact with the outer edge of the first dielectric member 34. By using such patch antennas 30, 30A, 30B, 30C, and 30E, it is possible to improve the gain at low elevation angles.

[0111] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. Furthermore, the present invention may be modified or improved without departing from the spirit thereof, and the present invention includes equivalents thereof. [Explanation of symbols]

[0112] 1 vehicle 2 roof panels 3 Roof lining 4 cavities 10. Vehicle antenna device 11. Base 11a Base 12 cases 21~26 Antenna 30, 30A~30E Patch Antenna 31,33 patterns 31a Circuit pattern 31b Ground Pattern 32 Circuit Board 34 First dielectric member Area 34a~34d 35 Radiating element 35p center point 36-40 Second dielectric member 41 Through hole 42 Power line 43a Power supply point 45 Coaxial Cable 45a signal line 45b braid 50 Shield cover

Claims

1. a radiating element; a first dielectric member on which the radiating element is provided; at least one second dielectric member provided around the first dielectric member; Equipped with the second dielectric member has a higher dielectric constant than the first dielectric member; The second dielectric member has a relative dielectric constant of 30 or more. Patch antenna.

2. a radiating element; a first dielectric member on which the radiating element is provided; at least one second dielectric member provided around the first dielectric member; Equipped with The thickness of the second dielectric member is approximately the same as or smaller than the thickness of the first dielectric member. Patch antenna.

3. A radiating element for receiving a circularly polarized electromagnetic wave; a first dielectric member on which the radiating element is provided; a plurality of second dielectric members provided around the first dielectric member; Equipped with Each of the plurality of second dielectric members is provided parallel to an outer edge of the first dielectric member. Patch antenna.

4. A radiating element for receiving linearly polarized waves; a first dielectric member on which the radiating element is provided; a plurality of second dielectric members provided around the first dielectric member; Equipped with the plurality of second dielectric members are provided at positions facing each other across the radiating element in a line direction connecting a feed point of the radiating element and a center point in the shape of the radiating element, Patch antenna.

5. The second dielectric member has a higher dielectric constant than the first dielectric member. The patch antenna according to any one of claims 2 to 4.

6. The second dielectric member has a relative dielectric constant of 30 or more. The patch antenna according to claim 5 .

7. The thickness of the second dielectric member is approximately the same as or smaller than the thickness of the first dielectric member.

5. A patch antenna according to any one of claims 1, 3 and 4.

8. The radiating element is an element that receives a circularly polarized electromagnetic wave.

3. The patch antenna according to claim 1 or 2.

9. the second dielectric member is formed in a shape surrounding the first dielectric member; 9. The patch antenna according to claim 3 or 8.

10. The second dielectric member is provided in plurality, Each of the plurality of second dielectric members is provided parallel to an outer edge of the first dielectric member. The patch antenna according to claim 8.

11. the radiating element is an element that receives linearly polarized electromagnetic waves, The second dielectric member is provided in plurality, the plurality of second dielectric members are provided at positions facing each other across the radiating element in a line direction connecting a feed point of the radiating element and a center point in the shape of the radiating element, 3. The patch antenna according to claim 1 or 2.

12. The second dielectric member is in contact with the outer edge of the first dielectric member. A patch antenna according to any one of claims 1 to 11.

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