JP2016001791A - Antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna device capable of appropriately securing a gain in a desired direction, while suppressing an increase in size and bad influence onto appearance.SOLUTION: An antenna device 5 comprises a radiation element 11 having a feeding point 12, and at least one resonator 20. The radiation element 11 is arranged on a bottom board 3. The resonator 20 is arranged in a recess part 3a formed on the bottom board 3. A height of the resonator on the basis of a plate surface of the bottom board 3 is lower than that of the radiation element.

Description

  The present invention relates to an antenna device.

  As various antenna devices mounted on a vehicle, an antenna device that is mounted on the roof of the vehicle is known. When the antenna device is attached to the roof of the vehicle, the horizontal gain may not be sufficiently obtained due to the influence of diffraction or the inclination of the roof.

  On the other hand, in Patent Document 1, by providing the antenna ground at a predetermined distance from the roof surface in a vertical direction, it is possible to ensure a line of sight from the antenna element to the front of the vehicle and to appropriately secure a gain in the front of the vehicle. An antenna device is described.

JP 2013-2223023 A

  However, if the antenna ground is separated from the vehicle roof surface in the vertical direction, the height of the entire antenna device inevitably increases, leading to an increase in size of the antenna device. Increasing the size of the antenna device mounted on the roof is not preferable in terms of appearance.

  The present invention has been made in view of the above problems, and an object thereof is to provide an antenna device capable of appropriately securing a gain in a desired direction while suppressing an increase in size and an adverse effect on the appearance. And

  The antenna device of the present invention made to solve the above problems includes a ground plane, a radiating element, and at least one resonator. The ground plane has a plate shape, and is formed with at least one concave portion having a predetermined depth recessed from the plate surface in a specific depth direction perpendicular to the plate surface. The radiating element has a feeding point and is disposed on the ground plane. This radiating element has a predetermined height in the height direction opposite to the depth direction from the plate surface of the ground plane. The resonator is disposed on the ground plane in the concave portion, which is the ground plane in the region in the concave portion of the ground plane, and the height from the plate surface of the ground plane is lower than that of the radiating element.

  Since the antenna device configured as described above includes a resonator separately from the radiating element, the resonator is operated as a reflector or a director for the radiating element by appropriately setting the resonance frequency of the resonator. It is possible. Moreover, the height of the resonator is lower than that of the radiating element. Therefore, it is possible to provide an antenna device capable of appropriately securing a gain in a desired direction while suppressing an increase in the size of the entire device and suppressing adverse effects on the appearance.

In the present invention, in order to make the height of the resonator lower than that of the radiating element, the resonator is arranged in a recess formed in the ground plane.
In this way, the ground plate is not a ground plate having a flat structure with no depressions on the entire surface, but a ground plate in which a recess is formed in part is used, and a resonator is arranged in the recess, thereby radiating element The relative height of the resonator relative to can be made lower.

  In addition, the code | symbol in the parenthesis described in the claim shows the correspondence with the specific means as described in embodiment mentioned later as one aspect, Comprising: The technical scope of this invention is limited is not.

It is explanatory drawing which shows schematic structure of the antenna apparatus of a reference example. (A) is a perspective view of the antenna device of a reference example, (b) is a top view of the antenna device of a reference example. (A) is explanatory drawing which shows the example of a dimension of the resonator (reflector) of a reference example, (b) is explanatory drawing which shows the frequency characteristic of the resonator. It is explanatory drawing for demonstrating the electric power radiated | emitted from the antenna apparatus of a reference example. (A) is a perspective view of the antenna apparatus of 1st Embodiment, (b) is a schematic sectional drawing of the antenna apparatus. It is explanatory drawing which shows the relationship between the gap g0 and the gain of a vehicle forward direction in the antenna device of 1st Embodiment. It is explanatory drawing which shows the horizontal surface directivity of an antenna apparatus. (A) is a perspective view of the resonator of 2nd Embodiment, (b) is a top view of the resonator. It is a perspective view of the antenna apparatus of 3rd Embodiment. It is a perspective view of the antenna apparatus of 4th Embodiment. It is a perspective view which shows the other Example of an antenna apparatus.

Preferred embodiments of the present invention will be described below with reference to the drawings.
[Reference example]
Before showing a specific example of the antenna device of the present invention, first, a basic configuration example in which some of the components of the antenna device of the present invention are omitted will be described as a reference example.

  As shown in FIG. 1, the antenna device 5 of the present reference example is mounted on the rear side of the vehicle 1 on the roof 3 of the vehicle 1. The roof 3 is a conductor, and also functions as a ground (ground plate) of the antenna device 5 in this reference example. Therefore, in the following description, “roof” means the ground of the antenna device 5 unless otherwise specified.

  In FIG. 1, a horizontal line L1 is a line parallel to the ground on which the vehicle travels. As apparent from FIG. 1, the plate surface of the roof 3 is not parallel to the horizontal line L1 but is inclined. That is, the rear side of the entire roof 3 where the antenna device 5 is mounted is slightly inclined toward the vehicle rear side with respect to a plane parallel to the ground (hereinafter also referred to as “horizontal plane”) as shown in FIG. Yes.

  The antenna device 5 is entirely covered with a cover 7. Therefore, when the vehicle 1 is viewed from the outside of the vehicle 1, the cover 7 on the roof 3 is directly visible, and the antenna device 5 in the cover 7 is not directly visible.

  The antenna device 5 mounted on the roof 3 while being covered with the cover 7 includes a monopole antenna 10 and a resonator 20 as shown in FIGS. 1 and 2. The resonator 20 functions and operates as a reflector in this reference example. Therefore, in this reference example, the resonator 20 is also referred to as a reflector 20. The monopole antenna 10 and the reflector 20 are arranged on the roof 3 at a predetermined distance in the front-rear direction of the vehicle 1.

  The monopole antenna 10 includes a monopole element 11 and a feeding point 12. The monopole element is erected vertically from the plate surface of the roof 3 with respect to the plate surface. One end of the monopole element 11 on the plate surface side of the roof 3 is a feeding point 12, and a feeding line (not shown) is connected to the feeding point 12. Power supply to the monopole element 11 is performed from the power supply point 12.

  The height of the monopole antenna 10, that is, the vertical distance from the plate surface of the roof 3 to the other end of the monopole element 11, is h1, as shown in FIG. The height h1 is also the length (element length) of the monopole element 11.

  In this reference example, the center frequency f1 of the radio wave transmitted and received by the antenna device 5 is 760 MHz, for example. Therefore, the monopole antenna 10 is configured to resonate at the same frequency f1 as the center frequency f1. Specifically, the length of the monopole element 11 is about ¼ of the wavelength corresponding to the center frequency f1.

  The reflector (resonator) 20 is disposed on the rear side in the front-rear direction of the vehicle 1 with respect to the monopole antenna 10. As shown in FIGS. 1 and 2, the reflector (resonator) 20 includes a patch 21, a conductor post 22, and a short pin 23. That is, the reflector 20 of this reference example is configured as an annular patch antenna that operates in the TM01 mode. However, the reflector 20 is not directly fed and functions as a parasitic element in the antenna device 5.

  The patch 21 is a disk-shaped conductor. The conductor support 22 is a cylindrical conductor and is erected on the roof 3. A patch 21 is connected to one end of the conductor post 22, and the other end is connected to the roof 3. That is, the patch 21 is physically supported by the conductor support 22 at the center thereof, and is electrically connected to the roof 3 by the conductor support 22.

  Note that the patch 21 is supported by the conductor support 22 so that the plate surface thereof is parallel to the plate surface of the roof 3. Further, the central axis of the patch 21 (a line passing through the center of the patch 21 and perpendicular to the plate surface of the patch 21) coincides with the axis of the conductor support post 22.

  The short pin 23 is a rod-shaped conductor, and one end is connected to the patch 21 and the other end is connected to the roof 3. Therefore, the patch 21 and the roof 3 are short-circuited by the short pin 23. The short pin 23 is erected vertically with respect to the plate surface of the roof 3.

  In the present reference example, the reflector 20 operates as the reflector 20 with respect to the monopole antenna 10, but the reflector 20 alone is a so-called resonator. If a resonator having a resonance frequency higher than the resonance frequency f1 of the monopole antenna 10 is used as the resonator, the resonator operates as a waveguide. On the other hand, in this reference example, a resonator whose resonance frequency f2 is slightly lower than the resonance frequency f1 of the monopole antenna 10 is used as the resonator 20, and thus the resonator 20 operates as a reflector.

  In the resonator 20, the direction of the electric field at the time of resonance is the same as the direction of the electric field at the time of resonance in the monopole antenna 10. That is, the electric field direction at the time of resonance of the monopole antenna 10 is the length direction (vertical direction) of the monopole element 11. On the other hand, the electric field direction at the time of resonance of the resonator 20 is also the standing direction (vertical direction) of the short pin 23.

  The resonator 20 of this reference example is an annular patch antenna. The resonance frequency of the annular patch antenna varies depending on the position of the short pin 23. More specifically, the resonance frequency f2 of the resonator 20 varies depending on the distance r in the plate surface direction from the center of the patch 21 to the axis of the short pin 23 (see FIG. 2B). The distance r can also be said to be the distance in the plate direction between the axis of the conductor support 22 and the short pin 23. The plate surface direction is a direction parallel to the plate surface of the roof 3. The resonance frequency f2 of the resonator 20 can be changed by adjusting the distance r. In this reference example, the resonance frequency f2 of the resonator 20 is slightly lower than the resonance frequency f1 of the monopole antenna 10.

  The height of the reflector 20, that is, the vertical distance from the plate surface of the roof 3 to the upper surface of the patch 21 of the reflector 20 is h 2 as shown in FIG. The height h <b> 2 of the reflector 20 is lower than the height h <b> 1 of the monopole antenna 10.

  As shown in FIG. 2B, the axis of the monopole element 11, the axis of the short pin 23, and the center of the patch 21 (axis of the conductor support 22) are aligned on a straight line. . The distance in the plate direction from the center of the patch 21 to the axis of the short pin 23 is r as described above. The distance in the plate surface direction from the center of the patch 21 to the axis of the monopole element 11 is R. In the present reference example, the distance R is approximately ¼ of the wavelength λ corresponding to the center frequency f1.

  In addition, the resonance frequency of the resonator 20 can be arbitrarily set by adjusting the dimensions (length based on the wavelength λ) of each part of the resonator 20 including the distance r. In this reference example, in order to operate the resonator 20 as a reflector, the dimensions of each part of the resonator 20 are determined so that the resonance frequency f2 of the resonator 20 is slightly lower than the center frequency f1.

  FIG. 3A shows an example of the size of each part for operating the resonator 20 as a reflector having the resonance frequency f2. The resonance characteristics of the resonator 20 illustrated in FIG. 3A are as shown in FIG. The dimensions illustrated in FIG. 3A take into account the size and shape of the roof 3 that functions as a ground plane. That is, the dimensions are such that desired resonance characteristics can be obtained when mounted on the roof 3. By determining the dimensions of each part of the resonator 20 as illustrated in FIG. 3A, resonance characteristics that resonate at a frequency f2 (a frequency slightly lower than f1) can be obtained as illustrated in FIG. 3B. .

  In addition, the example of the dimension shown to Fig.3 (a) is an example in case a dielectric is not filled between the patch 21 and the roof 3, but it is a space. When a dielectric is filled between the patch 21 and the roof 3, it is necessary to determine the dimensions of each part in consideration of the wavelength shortening rate due to the dielectric.

  The outline of the power radiated from the antenna device 5 in the vehicle front-rear direction will be described with reference to FIG. As illustrated in FIG. 4, the power Pf is radiated from the antenna device 5 to the area on the front side of the vehicle, and the power Pb is radiated to the area on the rear side of the vehicle.

  Of the entire radiated power Pf to the area on the front side of the vehicle, the component radiated in the elevation direction with respect to the plate surface of the ground plane 3 is Pf1, the component radiated in the direction parallel to the plane of the ground plane 3 is Pf2, and the ground plane A component radiated in a depression direction with respect to the plate surface 3 and in a direction parallel to the ground (horizontal plane) (that is, in front of the vehicle) is defined as Pf3. Of each component of the electric power Pf radiated from the antenna device 5 to the region on the front side of the vehicle, the radiated electric power toward the vehicle front (horizontal plane direction) is Pf3.

  On the other hand, out of the entire radiated power Pb to the region on the rear side of the vehicle, the radiation is radiated in a direction parallel to the ground surface (horizontal plane) (that is, the vehicle rear direction) with respect to the plate surface of the ground plane 3 The component is Pb1, the depression direction with respect to the horizontal plane and the component radiated in the direction parallel to the plane of the ground plane 3 is the depression direction with respect to both Pb2, the horizontal plane and the plane plane of the ground plane 3 The component to be radiated is Pb3.

  Of the power Pb radiated from the antenna device 5 to the vehicle rear side region, Pb2 and Pb3 are reflected by the reflector 20 to the vehicle front side region. The reflected wave is also spread and radiated to the area in front of the vehicle. When the reflected wave is divided into three components in the same way as the electric power directly radiated to the vehicle front side region, the component in the same direction as Pf1 is Pb′1, the component in the same direction as Pf2 is Pb′2, The component in the same direction as Pf3 is Pb′3.

  Therefore, the power of Pf3 + Pb′3 is radiated to the front side (horizontal direction) of the entire area on the front side of the vehicle as the antenna device 5 as a whole. That is, the gain toward the front of the vehicle increases by the amount of reflected power from the reflector 20.

  At least the electric power of Pb1 is propagated behind the vehicle. In this reference example, it is required for the antenna device 5 to be able to communicate mainly with the front of the vehicle. Therefore, the higher the vehicle forward gain, the better. However, a gain of a certain level or more is also required in the vehicle rear direction.

  On the other hand, in this reference example, the height h2 of the reflector 20 is sufficiently lower than the height h1 of the monopole antenna 10, and only a part (Pb2 + Pb3) of the radiated power to the rear region is reflected by the reflector 20. Since the other (Pb1) propagates backward, the necessary gain is ensured for the rear of the vehicle. Moreover, of the power radiated to the rear region, the power reflected by the reflector 20 is mainly radiated power Pb2 + Pb3 radiated in the depression direction with respect to the horizontal plane. That is, the electric power Pb1 in the horizontal direction is propagated backward with almost no reflection, and the electric power Pb2 + Pb3 in the depression direction is reflected by the reflector 20. The reflected wave is radiated with a spread toward the front of the vehicle. Therefore, it is possible to sufficiently secure the gain in front of the vehicle without significantly affecting the gain in the rear of the vehicle.

  The above description based on FIG. 4 explains the outline of the function of the antenna device 5, that is, the fact that a reflected wave is added to the radiated power to the front of the vehicle and the gain to the rear of the vehicle is appropriately secured. It is a conceptual explanation for doing. Therefore, how much the component in which direction of the radiated power Pb to the region on the vehicle rear side is reflected, how the reflected wave is radiated to the region on the vehicle front side, etc. The distribution state of the radiated power in the antenna device 5 including is not necessarily expressed accurately and precisely.

  As described above, the antenna device 5 of the present reference example includes the reflector 20 in addition to the monopole antenna 10. Moreover, the height h2 of the reflector 20 is sufficiently lower than the height h1 of the monopole antenna 10. Therefore, it is possible to provide the antenna device 5 that can appropriately secure a gain in a desired direction while suppressing an increase in the size of the entire device and suppressing adverse effects on the appearance.

  In this reference example, the antenna device 5 is required to have a predetermined level of gain in both the forward direction and the backward direction of the vehicle, and in particular, a higher gain is required in the forward direction of the vehicle. The antenna device 5 of the present reference example sufficiently satisfies such a gain requirement.

[First Embodiment]
Next, the antenna device 30 of the first embodiment to which the present invention is applied will be described with reference to FIG. Similar to the antenna device 5 of the reference example, the antenna device 30 of the first embodiment is mounted on the roof 3 of the vehicle 1 and includes a monopole antenna 10 and a resonator 40. The main configuration of the antenna device 30 of the first embodiment that is different from the antenna device 5 of the reference example is that a concave portion 3a is formed in a roof 3 as a ground plane, and a resonator 40 is provided in the concave portion 3a. Is that it is arranged.

  As shown in FIG. 5, the recess 3 a has a predetermined circular area in the roof 3 (an area on the vehicle rear side with respect to the monopole antenna 10) in a lower direction (depth direction) than the plate surface of the roof 3. It is formed by having a shape recessed by a depth h01. That is, the cylindrical space in the roof 3 that is recessed from the plate surface by the depth h01 is the recess 3a. The concave bottom surface 3b which is the bottom surface of the concave portion 3a is also a part of the roof 3 and functions as a ground plane of the antenna device 30.

  And the resonator 40 is arrange | positioned on the recessed part bottom face 3b. That is, the resonator 40 is embedded in the roof 3. The configuration and dimensions of the resonator 40 are the same as those of the resonator 20 of the reference example. That is, the resonator 40 according to the first embodiment includes a patch 41, a conductor post 42, and a short pin 43, and functions as a reflector for the monopole antenna 10. Therefore, in the following description, the resonator 40 according to the first embodiment is also referred to as a reflector 40. In the first embodiment as well, the axis of the monopole element 11, the axis of the short pin 43, and the center of the patch 41 (axis of the conductor support column 42) are aligned on a straight line. It is out.

  The height h02 of the reflector 40 with respect to the plate surface of the recess bottom surface 3b is the same as the depth h01 of the recess 3a. Therefore, the plate surface of the roof 3 and the plate surface of the patch 41 constituting the reflector 40 are on the same plane. In other words, the reflector 40 arranged on the concave bottom surface 3b has a height from the concave bottom surface 3b that is the surface of the roof 3 (specifically, the surface of the entire roof 3 other than the concave portion 3a). It is arranged not to exceed.

An interval (gap) g0 between the outer peripheral end of the patch 41 and the opening end of the recess 3a is the same as the length of the short pin 43 in this embodiment.
As shown in FIG. 6, as the gap g0 becomes smaller than the length of the short pin 43, the gain of the antenna device 30 in the vehicle front direction becomes smaller. Conversely, even if the gap g0 is made longer than the length of the short pin 43, the gain in the vehicle front direction of the antenna device 30 is not much different from the gain in the case of the same length as the short pin 43. Therefore, in the first embodiment, the gap g0 is the same length as the short pin 43. In addition, you may make it cover the opening part between the outer periphery end of the patch 41, and the opening end of the recessed part 3a with an insulator. By doing so, the presence of the reflector 40 can be made inconspicuous in appearance.

  The horizontal plane directivity of the antenna device 30 according to the first embodiment is shown in FIG. For comparison, FIG. 7A shows a configuration in which the reflector 40 is omitted from the antenna device 30, that is, the horizontal plane directivity of the antenna device including only the monopole antenna 10. FIG. 7 shows a case where the center frequency f1 of the used frequency band is 760 MHz, and the length of the monopole element 11 is set to a length obtained by further multiplying the wavelength corresponding to the center frequency f1 by 0.95. It is a simulation result of horizontal plane directivity.

  As shown in FIG. 7A, when only the monopole antenna 10 is used and the reflector 40 is not provided, the gain in the front of the vehicle is about 1 dB lower than the gain in the rear of the vehicle due to the inclination of the surface of the roof 3. ing. On the other hand, as shown in FIG. 7B, the antenna device 30 of the first embodiment has an increased gain in the front of the vehicle while suppressing a decrease in gain in the rear of the vehicle. That is, as compared with FIG. 7A, the gain in the front of the vehicle is effectively improved without substantially affecting the gain in the rear of the vehicle.

  According to the antenna device 30 of the first embodiment described above, the reflector 40 is embedded in the recess 3 a of the roof 3. Therefore, the relative height of the reflector 40 with respect to the monopole antenna 10 is suppressed to be lower than that in the reference example. Thereby, in addition to the effect similar to the antenna apparatus 5 of a reference example, the influence on an external appearance can be suppressed more. In particular, in the first embodiment, the plate surface of the roof 3 and the plate surface of the patch 41 are on the same plane. Therefore, as a result, it is almost inconspicuous that the concave portion 3a is formed in the roof 3, and an adverse appearance is suppressed.

  In addition, the shape of the recessed part 3a does not necessarily need to be exact | strict cylindrical shape. For example, as shown by an arc-shaped broken line in FIG. 5B, the shape may be a shape in which the inclination changes smoothly (in an arc shape) from the side surface to the bottom surface.

[Second Embodiment]
A modification of the resonator constituting the antenna device will be described as a second embodiment. As shown in FIG. 8, the resonator 50 according to the second embodiment includes a patch 51 and a conductor post 52, similarly to the resonator 40 according to the first embodiment. These shapes and dimensions are the same as those of the resonator 40. Further, similarly to the resonator 40 of the first embodiment, the resonator 50 of the second embodiment has a height in the recess 3a formed in the roof 3 so that the height does not exceed the plate surface of the roof 3. Has been placed.

  The resonator 50 of the second embodiment is different from the first embodiment in that it includes four short pins and can selectively enable any one of the short pins. It is a configuration.

  Specifically, the resonator 50 according to the second embodiment includes four short pins, that is, a first short pin 61, a second short pin 62, a third short pin 63, and a fourth short pin 64. . The distance r in the plate surface direction from the center of the patch 51 to the axis of each of the short pins 61 to 64 is the same. The short pins 61 to 64 are arranged at 90 ° intervals in the circumferential direction of the patch 51 as viewed from the center of the patch 51.

  The first short pin 61 includes a conductor portion 61a and a switch 61b. When the switch 61b is turned off, the conduction state between the patch 51 and the roof 3 by the first short pin 61 is cut off. That is, the function of the first short pin 61 as a short pin is invalidated. When the switch 61b is turned on, the conduction state between the patch 51 and the roof 3 is validated. That is, the patch 51 and the roof 3 are electrically connected via the conductor portion 61a and the switch 61b, whereby the first short pin 61 functions as a short pin. The other three short pins 62, 63, 64 have the same configuration as the first short pin 61.

  Each switch 61b, 62b, 63b, 64b is individually turned on and off by a control signal from the switch control unit 60. The switch control unit 60 has at least a function of turning on only one of the switches 61b, 62b, 63b, and 64b and turning off the other three. That is, it has a function of enabling only one of the four short pins 61 to 64.

  By switching the short pin to be activated, the distance between the monopole antenna 10 and the resonator 50 can be changed equivalently. Therefore, the directivity of the whole antenna device can be changed by switching the short pin to be activated. Note that the resonator 50 of the second embodiment may be operated as the above-described reflector, or may be operated as a waveguide described later.

[Third Embodiment]
The antenna device 70 according to the third embodiment will be described with reference to FIG. The antenna device 70 of the third embodiment is further provided with a resonator 80 (hereinafter also referred to as “waveguide 80”) that operates as a director with respect to the antenna device 30 (see FIG. 5) of the first embodiment. It has a configuration provided. The director 80 is disposed in front of the vehicle with respect to the monopole antenna 10.

  As with the reflector 40, the director 80 includes a patch 81, a conductor post 82, and a short pin 83. The director 80 is different from the reflector 40 in the distance in the plate surface direction from the center of the patch 81 to the short pin 83. The director 80 is configured such that its resonance frequency f3 is slightly higher than the resonance frequency f1 of the monopole antenna 10.

In addition, the director 80 is embedded in a recess formed in the roof 3 just like the reflector 40.
The axis of the monopole element 11, the axis of the short pin 43 of the reflector 40, the center of the patch 41 of the reflector 40 (the axis of the conductor post 42), and the axis of the short pin 83 of the director 80 And the center of the patch 81 of the waveguide 80 (the axial center of the conductor support 82) are aligned in a straight line in the plate surface direction. The distance in the plate direction between the monopole element 11 and the short pin 83 of the director 80 is the same as the distance R in the plate direction between the monopole element 11 and the short pin 43 of the reflector 40 (corresponding to the center frequency f1). The wavelength λ is approximately 1/4).

  As described above, the reflector 40 is provided on the rear side of the monopole antenna 10 and the director 80 is provided on the front side of the monopole antenna 10, so that the vehicle front side can be compared with an antenna device that does not have the director 80. The gain can be further increased.

[Fourth Embodiment]
The antenna apparatus 90 of 4th Embodiment is demonstrated using FIG. The antenna device 90 of the fourth embodiment has a configuration in which two further directors are added to the antenna device 70 (see FIG. 9) of the third embodiment. Specifically, two directors 110 and 120 are further provided for the antenna device 70 of the third embodiment. One of the two directors 110 and 120 is disposed in the vehicle right direction with respect to the monopole antenna 10, and the other director 120 is disposed with respect to the monopole antenna 10. It is arranged in the left direction of the vehicle.

  The structures of these two waveguides 110 and 120 are exactly the same as the waveguide 80 on the front side of the monopole antenna 10. In addition, these two waveguides 110 and 120 are both embedded in a recess formed in the roof 3 just like the waveguide 80 on the front side of the monopole antenna 10.

  The axis of the monopole element 11, the axis of the short pin 113 of the director 110, the center of the patch 111 of the director 110 (the axis of the conductor support 112), and the short pin of the director 120 The axial center of 123 and the center of the patch 121 of the director 120 (axial center of the conductor support column 122) are aligned on a straight line in the plate surface direction. The distance in the plate surface direction between the monopole element 11 and each short pin 113, 123 of each director 110, 120 is the plate surface direction between the monopole element 11 and the short pin 43 of the reflector 40. Is equal to the distance R (approximately ¼ of the wavelength λ corresponding to the center frequency f1).

  As described above, the reflector 40 is provided on the rear side of the monopole antenna 10 and the plurality of directors 80, 110, 120 are provided from the side of the monopole antenna 10 to the front, thereby having one director. Compared with the antenna device 70 of the third embodiment, the gain ahead of the vehicle can be increased.

[Other Embodiments]
(1) When embedding the resonator in the concave portion of the roof 3, it is not essential to make the patch 41 of the resonator 40 and the roof surface the same surface as in the antenna device 30 of the first embodiment. The patch may protrude above the plate surface of the roof 3, or conversely, the patch may be positioned below the plate surface of the roof 3. However, considering the appearance, it is preferable to completely embed the resonator in the recess. In particular, when the resonator is operated as a reflector, it is preferable that the resonator is completely embedded in the concave portion in order to suppress a decrease in radiation gain in the direction of the reflector as viewed from the radiation element 11. . Further, considering the appearance, it is preferable that the plate surface of the roof 3 and the plate surface of the patch 41 constituting the resonator 40 be the same surface as in the first embodiment.

  (2) The shape of the patch constituting the resonator is not limited to a circle. For example, it may be polygonal. Also about the conductor support | pillar which comprises a resonator, not only cylindrical shape but polygonal prism shape may be sufficient, for example.

  (3) In each of the above embodiments, a circular patch antenna having a patch, a conductor post, and a short pin is employed as the resonator. However, the specific configuration of the resonator is not limited to the circular patch antenna. For example, antennas having various configurations such as an inverted L antenna, an inverted F antenna, and a half-loop antenna can be used as a parasitic resonator.

  (4) The number of resonators can be determined as appropriate. Further, when a plurality of resonators are provided, it is possible to appropriately determine where each is provided with respect to the monopole antenna 10 and which of the resonator and the reflector is operated.

  In the fourth embodiment, the antenna device 90 (see FIG. 10) having a plurality of directors is shown, but how many and where to provide a plurality of directors can be determined as appropriate. . For example, a plurality of waveguides 80 and 130 may be sequentially arranged in front of the monopole antenna 10 as in the antenna device 140 shown in FIG.

  In the antenna device 140 of FIG. 11, the axis of the monopole element 11, the axis of the short pin 83 of the director 80, the center of the patch 81 of the director 80 (the axis of the conductor support 82), the conductor The axis of the short pin 133 of the waver 130 and the center of the patch 131 of the waver 130 (the axis of the conductor support column 132) are aligned in a straight line in the plate surface direction. The distance in the plate surface direction of each short pin 83, 133 of each director 80, 130 is the same as the distance between the monopole element 11 and the waveguide unless the patches 81, 131 of each director 80, 130 interfere. The distance R is preferably the same as the distance R of the 80 short pins 83.

  Moreover, you may comprise the antenna apparatus provided with only one or more waveguides as a resonator. Specifically, the reflector 40 may be omitted from the antenna device 70 of the third embodiment shown in FIG. The reflector 40 may be omitted from the antenna device 90 of the fourth embodiment shown in FIG. 10, or the reflector 40 may be omitted from the antenna device 140 shown in FIG.

  (5) When a plurality of resonators are provided, at least one or all of the resonators are provided with a plurality of short pins as in the resonator 50 of the second embodiment, and one of them can be activated. It is good also as a vessel.

  (6) In the resonator 50 shown in the second embodiment, the four short pins 61 to 64 are all provided at a distance r from the center of the patch 51. Where are a plurality of short pins provided? Can be determined as appropriate. For example, the distance r from the center of the patch 51 may be different for each of the plurality of short pins. In this case, the resonance frequency of the resonator can be changed by switching the short pin to be activated. Therefore, the same single resonator can be operated as a waveguide or a reflector by switching the short pin.

  (7) In each of the above embodiments, the monopole element 11 is used as the radiating element, but this is merely an example. As the radiating element, an element (antenna element) other than the monopole element may be used.

(8) The present invention is not limited to application to an antenna device mounted on the vehicle 1. You may apply this invention with respect to the antenna apparatus used for uses other than mounting to a vehicle.
(9) In addition, the present invention is not limited to the specific means and structure shown in the above embodiment, and can take various forms without departing from the gist of the present invention. For example, a part of the configuration of the above embodiment is replaced with a known configuration having the same function, added to or replaced with the configuration of another embodiment, or omitted as long as the problem can be solved. May be. Moreover, you may comprise combining several said embodiment suitably.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 3 ... Roof, 3a ... Recessed part, 3b ... Recessed bottom face, 5, 30, 70, 90, 140 ... Antenna apparatus, 7 ... Cover, 10 ... Monopole antenna, 11 ... Monopole element, 12 ... Feeding point , 20, 40... Resonator (reflector), 21, 41, 51, 81, 111, 121, 131... Patch, 22, 42, 52, 82, 112, 122, 132 .. conductor post, 23, 43, 83. , 113, 123, 133... Short pin, 50... Resonator, 60... Switch control unit, 61... First short pin, 61a, 62a, 63a, 64a ... Conductor unit, 61b, 62b, 63b, 64b. ... 2nd short pin, 63 ... 3rd short pin, 64 ... 4th short pin, 80, 110, 120, 130 ... Resonator (waveguide).

Claims (10)

A plate-like ground plate, wherein the ground plate (3) is formed with at least one recess (3a) recessed from the plate surface by a predetermined depth in a specific depth direction perpendicular to the plate surface;
A radiating element (11) disposed on the ground plane, having a feeding point, and having a predetermined height in a height direction opposite to the depth direction from the plate surface of the ground plane;
At least one resonator (40, 50, 80, 110, 120, 130) disposed on a concave ground plane (3b) that is a ground plane in the concave portion of the ground plane;
With
The antenna device (30, 70, 90, 140), wherein the at least one resonator has a height from the plate surface of the ground plane lower than that of the radiating element. The antenna device according to claim 1,
The antenna device, wherein the resonator is formed such that a height from the ground plate in the recess does not exceed a plate surface of a region other than the recess in the ground plate. The antenna device according to claim 1 or 2, wherein
One of the resonators operates as a reflector (20, 40, 50) for the radiating element. The antenna device according to any one of claims 1 to 3,
At least one of the resonators operates as a director (50, 80, 110, 120, 130) for the radiating element. Antenna device (70, 90, 140), characterized in that: The antenna device according to any one of claims 1 to 4, wherein
In the resonator, the height from the ground plane in the recess is lower than the height of the radiating element, and the direction of the electric field at the time of resonance is the same as the direction of the electric field at the time of resonance in the radiating element. An antenna device. The antenna device according to any one of claims 1 to 5,
The resonator is
Plate-like patch conductors (41, 51, 81, 111, 121, 131);
Conductor support portions (42, 52, 82, 112, 122, etc.) provided between the patch conductors and the ground plane, for supporting the patch conductors on the ground plane and conducting the ground plane and the patch conductors. 132),
A short pin (43, 61 to 64, 83, 113, 123, 133) provided between the patch conductor and the ground plane, separately from the conductor support, for conducting the patch conductor and the ground plane. When,
An antenna device comprising: an annular patch antenna. The antenna device according to claim 6, wherein
At least one of the annular patch antennas includes a plurality of the short pins,
A switch unit (61b, 62b, 63b, 64b) that is provided on each of the short pins, and switches the conduction state between the patch conductor and the ground plane by the short pin between valid and invalid;
A control unit (60) capable of enabling the conduction state only for any one of the short pins by individually controlling the switch unit;
An antenna device comprising: The antenna device according to any one of claims 1 to 7,
The antenna device is characterized in that the radiating element is a monopole element. The antenna device according to any one of claims 1 to 8, wherein
The antenna device is arranged on a roof (3) of a vehicle (1), and the roof functions as the base plate. The antenna device according to claim 9, wherein
At least one of the resonator that functions as a director and is disposed in front of the radiating element, and the resonator that functions as a reflector and disposed in the rear of the radiating element. An antenna device comprising: