Antenna Device

Abstract

To provide an antenna device that uses 0th order resonance, the antenna device capable of preventing leakage of current to a cable without providing a stripline.SOLUTION: An antenna device 1 comprises: a bottom board 10 that is a flat board conductor member; an opposite conductor plate 30 that is a flat board conductor member installed at a predetermined interval with the bottom board 10 and is electrically connected with a feeder line; and a short circuit unit 40 that is provided in a center area of the opposite conductor plate 30 and electrically connects the opposite conductor plate 30 and the bottom board 10 with each other, and the operation frequency of the antenna device is a frequency at which an inductance included in the short circuit unit 40 and a capacitance formed by the bottom board 10 and the opposite conductor plate 30 have parallel resonance. The short circuit unit 40 has a peripheral shape in a portion short circuited to the opposite conductor plate 30. In the opposite conductor plate 30, a circuit 50 is arranged in an area surrounded by the portion in which the short circuit unit 40 is short circuited.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an antenna device that utilizes zero-order resonance. [Background technology]

[0002] The antenna device is equipped with a ground plate, which is a conductive plate that provides a ground potential, in addition to the radiating element. If the area of ​​the ground plate is insufficient for the wavelength of the radio waves to be transmitted and received, there is a risk that the current leaking from the ground plate to the cable (hereinafter referred to as leakage current) will increase. If leakage current flows through the cable, the gain may decrease and the directivity may become unstable.

[0003] As a technique related to such an issue, Patent Document 1 discloses a technique in which a ground plane is formed of a printed circuit board and a ¼ wavelength strip line is formed on the ground plane.

[0004] As an antenna device utilizing zero-order resonance, there is known an antenna device that includes a flat base plate that functions as a ground, a flat opposing conductor plate that is arranged opposite the base plate and has a feed point provided at an arbitrary position, and a short-circuit portion that electrically connects the base plate and the opposing conductor plate (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4992762 [Patent Document 2] JP 2016-111655 A Summary of the Invention [Problem to be solved by the invention]

[0006] Antenna devices may be equipped with circuits for the purpose of controlling radio waves emitted from antenna elements. The circuits require a ground. In antenna devices that use zero-order resonance, it is possible to expand the ground plane for the circuits.

[0007] However, if the ground plate is enlarged and its length approaches the length at which the antenna device resonates at the frequency of the radio waves emitted by the antenna device (hereinafter, referred to as the operating frequency), there is a risk of an increase in leakage current. In order to prevent leakage current from flowing through the cable, it is possible to provide a stripline for suppressing leakage current, as disclosed in Patent Document 1. However, providing a stripline for suppressing leakage current requires an area for arranging the stripline, which reduces the area available for arranging circuit elements.

[0008] The present disclosure has been made based on the above circumstances, and its purpose is to provide an antenna device that utilizes zero-order resonance and is capable of suppressing leakage current into a cable without providing a stripline. [Means for solving the problem]

[0009] The antenna device to achieve this purpose includes a ground plate (10, 210) which is a flat conductive member, An opposing conductor plate (30, 230) which is a flat conductor member disposed at a predetermined distance from the ground plane and is electrically connected to the power supply line; a short circuit portion (40, 240) provided in a central region of the opposing conductor plate for electrically connecting the opposing conductor plate and the ground plate; An antenna device having an operating frequency that is a frequency at which an inductance of a short circuit portion and a capacitance formed by a ground plate and an opposing conductor plate resonate in parallel, The short-circuited portion is a circumferential portion that is short-circuited with the opposing conductor plate, In the opposing conductor plate, a circuit is disposed in a region surrounded by the short-circuited portion of the short circuit portion.

[0010] In this antenna device, the opposing conductor plate has an area surrounded by the short-circuited parts. The opposing conductor plate is electrically connected to the power feed line, but since current does not easily flow inside the area surrounded by the short-circuited parts, this area can be used as a circuit ground. Therefore, in this antenna device, a circuit is arranged in the opposing conductor plate in the area surrounded by the short-circuited parts.

[0011] Since the opposing conductor plate is used as the ground of the circuit, there is no need to expand the ground plate for the circuit to increase the portion that does not face the opposing conductor plate. Therefore, it is possible to prevent the length of the portion of the ground plate through which current flows from approaching the length at which it resonates at the operating frequency. As a result, there is no need for a stripline to suppress leakage current from the ground plate.

[0012] In addition, the symbols in parentheses in the claims indicate a correspondence with the specific means described in the embodiments described below as one aspect, and do not limit the technical scope of the present disclosure. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is an external perspective view of the antenna device 1. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II shown in FIG. [Diagram 3] 3 is a diagram showing the magnitude of an electric field vector generated in the antenna device 1. [Figure 4] FIG. 11 is a plan view of an antenna device 201 according to a second embodiment. [Diagram 5] FIG. 2 is a cross-sectional view of the antenna device 201. [Figure 6] 11 is a diagram showing the relationship between the length between adjacent short-circuit pins and the rate of inductance change. [Figure 7] FIG. 11 is a plan view of an antenna device 301 according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] First Embodiment Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the following, components having the same functions are denoted by the same reference numerals, and their description will be omitted. In addition, when only a part of the configuration is mentioned, the configuration of the embodiment described above can be applied to the other parts.

[0015] 1 is an external perspective view showing a schematic configuration of an antenna device 1 according to a first embodiment. The antenna device 1 is mounted on a moving object such as a vehicle and used.

[0016] The antenna device 1 is configured to transmit and receive radio waves at a predetermined operating frequency. Of course, in other embodiments, the antenna device 1 may be used for only one of transmission and reception. Since radio wave transmission and reception are reversible, a configuration capable of transmitting radio waves at a certain frequency is also a configuration capable of receiving radio waves at that frequency.

[0017] The operating frequency is set to 2.45 GHz as an example here. Of course, the operating frequency may be designed as appropriate, and may be, for example, 300 MHz, 760 MHz, 850 MHz, 900 MHz, 1.17 GHz, 1.28 GHz, 1.55 GHz, 5.9 GHz, etc. in other embodiments. The antenna device 1 is capable of transmitting and receiving not only the operating frequency, but also radio waves having frequencies within a predetermined range determined based on the operating frequency. For example, the antenna device 1 is configured to be capable of transmitting and receiving frequencies belonging to the band from 2400 MHz to 2500 MHz (hereinafter, 2.4 GHz band).

[0018] That is, the antenna device 1 is configured to be capable of transmitting and receiving radio waves in a frequency band used in short-range wireless communication such as Bluetooth Low Energy (Bluetooth is a registered trademark), Wi-Fi (registered trademark), ZigBee (registered trademark), etc. In other words, the antenna device 1 is configured to be capable of transmitting and receiving radio waves in a frequency band (so-called ISM band) allocated for general-purpose use in the industrial, scientific, and medical fields as specified by the International Telecommunication Union.

[0019] The antenna device 1 is connected to a communication ECU (Electronic Control Unit) mounted on a vehicle via a cable 2, and signals received by the antenna device 1 are sequentially output to the communication ECU. The antenna device 1 also converts electrical signals input from the communication ECU into radio waves and radiates them into space. The communication ECU utilizes the signals received by the antenna device 1 and supplies high-frequency power to the antenna device 1 according to the transmission signals.

[0020] 1, the antenna device 1 includes a ground plate 10, a support plate 20, an opposing conductor plate 30, and a short-circuit portion 40. For convenience, in the following description of each portion, the side on which the opposing conductor plate 30 is provided relative to the ground plate 10 is regarded as the upper side of the antenna device 1. In other words, the direction from the ground plate 10 toward the opposing conductor plate 30 corresponds to the upward direction of the antenna device 1. Moreover, the direction from the opposing conductor plate 30 toward the ground plate 10 corresponds to the downward direction of the antenna device 1.

[0021] The ground plate 10 is a plate-shaped conductor member made of a conductor such as copper. The ground plate 10 is provided along the lower surface of the support plate 20. The plate-shaped member includes a thin film such as a metal foil. That is, the ground plate 10 may be a plate formed by electroplating or the like on the surface of a resin plate such as a printed wiring board. The ground plate 10 may also be realized by using a conductor layer disposed inside a multilayer board including a plurality of conductor layers and insulating layers. This ground plate 10 provides a ground potential (in other words, a ground potential) in the antenna device 1. The ground plate 10 provides a ground potential by, for example, being electrically connected to the outer conductor of a coaxial cable. In the following description, unless otherwise specified, a connection means an electrical connection.

[0022] The ground plate 10 is formed in a rectangular shape. The X-axis shown in various drawings such as Fig. 1 represents the longitudinal direction of the ground plate 10, the Y-axis represents the lateral direction of the ground plate 10, and the Z-axis represents the up-down direction of the ground plate 10. The three-dimensional coordinate system having the X-axis, Y-axis, and Z-axis is a concept for explaining the configuration of the antenna device 1.

[0023] The ground plate 10 only needs to be larger than the opposing conductor plate 30. The dimensions of the ground plate 10 can be changed as appropriate. The length of one side of the ground plate 10 may be set to a value electrically smaller than one wavelength (for example, 1 / 3 of the operating wavelength). The operating wavelength is the wavelength of the radio waves radiated by the antenna device 1.

[0024] The shape of the ground plate 10 as viewed from above (hereinafter, referred to as the planar shape) can be changed as appropriate. Here, as an example, the planar shape of the ground plate 10 is rectangular, but in another embodiment, the planar shape of the ground plate 10 may be square. When the ground plate 10 is square, the direction along any one side can be set as the X-axis. The shape of the ground plate 10 may be other polygonal shapes. For example, the ground plate 10 may be square with one side set to a value electrically equivalent to one wavelength. The term "rectangle" includes rectangular and square shapes.

[0025] The support plate 20 is a plate-like member that serves to arrange the ground plate 10 and the opposing conductor plate 30 facing each other with a predetermined distance between them. The support plate 20 is a rectangular flat plate, and the size of the support plate 20 is approximately the same as that of the ground plate 10 in a plan view. The support plate 20 is realized using a dielectric material having a predetermined relative dielectric constant, such as glass epoxy resin. Here, as an example, the support plate 20 is realized using glass epoxy resin with a relative dielectric constant of 4.3.

[0026] The distance between the opposing conductor plate 30 and the ground plate 10 can be adjusted by adjusting the thickness of the support plate 20. The specific value of the thickness of the support plate 20 may be appropriately determined by simulation or testing.

[0027] The thickness of the support plate 20 also serves as a parameter for adjusting the length of the short-circuit portion 40, as described below. In other words, the thickness of the support plate 20 functions as a parameter for adjusting the inductance provided by the short-circuit portion 40. In addition, the thickness of the support plate 20 also serves as a parameter for adjusting the electrostatic capacitance formed by the ground plate 10 and the opposing conductor plate 30 facing each other.

[0028] The support plate 20 only needs to fulfill the above-mentioned role, and the shape of the support plate 20 can be changed as appropriate. The configuration for arranging the opposing conductor plate 30 facing the ground plate 10 may be a plurality of columns. In addition, in this embodiment, the space between the ground plate 10 and the opposing conductor plate 30 is filled with resin as the support plate 20, but this is not limited to this. The space between the ground plate 10 and the opposing conductor plate 30 may be hollow or vacuum. A honeycomb structure or the like may also be adopted as the support plate 20. Furthermore, the structures exemplified above may be combined. When the antenna device 1 is realized using a printed wiring board, a plurality of conductor layers provided on the printed wiring board may be used as the ground plate 10 and the opposing conductor plate 30, and a resin layer separating the conductor layers may be used as the support plate 20.

[0029] The opposing conductor plate 30 is a plate-shaped conductor member made of a conductor such as copper. As described above, the plate-shaped member includes a thin film such as copper foil. The opposing conductor plate 30 is disposed so as to face the base plate 10 via the support plate 20. The opposing conductor plate 30 may also be patterned on the surface of a resin plate such as a printed wiring board, similar to the base plate 10. In addition, "parallel" here does not necessarily mean a completely parallel state. It may be inclined at an angle of several degrees to about 30 degrees. In other words, it may include a state in which the two are roughly parallel (a so-called substantially parallel state). The term "vertical" in the present disclosure is also not limited to a completely vertical state, but also includes an inclination at an angle of several degrees to about 30 degrees.

[0030] The opposing conductor plate 30 and the ground plate 10 are arranged opposite to each other to form a capacitance according to the area of ​​the opposing conductor plate 30 and the distance between the opposing conductor plate 30 and the ground plate 10. The opposing conductor plate 30 is formed to a size that forms a capacitance that resonates in parallel with the inductance of the short circuit portion 40 at the operating frequency. The area of ​​the opposing conductor plate 30 may be appropriately designed to provide a desired capacitance. The desired capacitance is a capacitance that operates at the operating frequency in cooperation with the inductance of the short circuit portion 40. Note that, if the operating frequency is f, the inductance of the short circuit portion 40 is L, and the capacitance formed between the opposing conductor plate 30 and the ground plate 10 is C, the relationship f=1 / {2π√(LC)} is established. A person skilled in the art can determine an appropriate area of ​​the opposing conductor plate 30 based on the relational expression.

[0031] The planar shape of the opposing conductor plate 30 is rectangular in FIG. 1. That is, the shape of the opposing conductor plate 30 is similar to the planar shape of the ground plate 10. The long and short sides of the opposing conductor plate 30 are parallel to the long and short sides of the ground plate 10, respectively. However, the planar shape of the opposing conductor plate 30 may be a circle, a square, a regular octagon, a regular hexagon, or the like. Furthermore, the opposing conductor plate 30 may be provided with slits or have rounded corners.

[0032] A feed point 31 is formed on the opposing conductor plate 30. As shown in FIG. 2, the feed point 31 is the end of the feed pin 32 on the opposing conductor plate 30 side. A coaxial cable is connected to the opposite end of the feed pin 32. Thus, the feed pin 32 electrically connects the opposing conductor plate 30 to the coaxial cable. In FIG. 1, the feed point 31 is located near the midpoint of one of the short sides of the opposing conductor plate 30. However, the feed point 31 can be located at any position as long as the impedance can be matched with the feed line.

[0033] As a method for feeding power to the opposing conductor plate 30, various methods can be adopted, such as a direct feeding method and an electromagnetic coupling method. The direct feeding method refers to a method in which a feeder line is directly connected to the opposing conductor plate 30. The electromagnetic coupling method refers to a feeding method that utilizes electromagnetic coupling between a microstrip line or the like for feeding power and the opposing conductor plate 30.

[0034] 2, the tip of the cable 2 is connected to an end of the antenna device 1. The cable 2 is connected to a signal line such as a pattern line provided inside the antenna device 1. For example, by making the support plate 20 have a multi-layer structure, the signal line can be formed at a position in the thickness direction of the support plate 20 different from the ground plate 10 and the opposing conductor plate 30.

[0035] The short-circuiting portion 40 electrically connects the ground plate 10 and the opposing conductor plate 30. The short-circuiting portion 40 of the present embodiment is configured to include a plurality of short-circuiting pins 41. Note that, for convenience of illustration, only some of the short-circuiting pins 41 are labeled with reference numerals in FIG.

[0036] The short-circuiting pin 41 is a conductive member, and as shown in Fig. 2, one end is connected to the ground plate 10 and the other end is connected to the opposing conductor plate 30. The multiple short-circuiting pins 41 have the same shape and size. Each short-circuiting pin 41 is perpendicular to the opposing conductor plate 30 and the ground plate 10. By adjusting the diameter and length of the multiple short-circuiting pins 41, the inductance of the short-circuiting portion 40 can be adjusted.

[0037] The shorting pin 41 may be a hollow member, and in the case where the antenna device 1 is realized using a printed wiring board as a base material, a via provided in the printed wiring board can be used as the shorting pin 41.

[0038] The portions of the multiple short-circuiting pins 41 that are connected to the opposing conductor plate 30 are located on one rectangular circumference 42. In other words, when the multiple short-circuiting pins 41 connect the portions that are short-circuited with the opposing conductor plate 30, they form a circumference.

[0039] The rectangular perimeter 42 is disposed so that its center is near the center of the opposing conductor plate 30. The size of the perimeter 42 can be determined from the inductance required for the short-circuit portion 40. The size of the perimeter 42 may also be determined from the area required for the circuit 50 to be disposed in the portion surrounded by the perimeter 42 of the opposing conductor plate 30.

[0040] The intervals between the multiple short-circuiting pins 41 are set so that almost no current whose amplitude fluctuates at the operating frequency passes between the short-circuiting pins 41. In order to ensure that almost no current whose amplitude fluctuates at the operating frequency passes between the short-circuiting pins 41, the intervals between the multiple short-circuiting pins 41 are sufficiently narrow compared to the operating wavelength.

[0041] In the opposing conductor plate 30, a circuit 50 is disposed in an area surrounded by a periphery 42, i.e., an area surrounded by a portion where the short-circuit pin 41 is short-circuited. The circuit 50 is, for example, a transmitting / receiving circuit. The transmitting / receiving circuit is a circuit module that performs at least one of modulation, demodulation, frequency conversion, amplification, digital-to-analog conversion, and detection. The circuit 50 operates using the opposing conductor plate 30 as a circuit ground. A portion of the circuit 50 is connected to the opposing conductor plate 30 that functions as the circuit ground. The circuit 50 is also connected to the cable 2 via a pattern line or the like provided inside the support plate 20.

[0042] [Operation of antenna device 1] The operation of the antenna device 1 having the above-mentioned structure will be described. The opposing conductor plate 30 is short-circuited to the ground plate 10 at the short-circuiting part 40 provided in the central region thereof, and the area of ​​the opposing conductor plate 30 is set to an area that forms a capacitance that resonates in parallel with the inductance of the short-circuiting part 40 at the operating frequency.

[0043] Therefore, when a high-frequency signal is input from the power supply point 31, LC parallel resonance occurs due to energy exchange between the inductance and the capacitance. In order to achieve LC parallel resonance at the operating frequency, the length of the short-circuiting portion 40 may be shorter than the length at which primary resonance occurs. This LC parallel resonance is the zero-order resonance. When LC parallel resonance occurs, an electric field perpendicular to the ground plate 10 and the opposing conductor plate 30 is generated between the ground plate 10 and the opposing conductor plate 30. This perpendicular electric field propagates from the short-circuiting portion 40 toward the edge of the opposing conductor plate 30, and at the edge of the opposing conductor plate 30, the vertical electric field becomes a linearly polarized wave having a polarization plane perpendicular to the ground plate 10 (hereinafter, referred to as a ground vertically polarized wave) and propagates through space. Note that the ground vertically polarized wave here refers to an electric wave whose electric field vibration direction is perpendicular to the ground plate 10 and the opposing conductor plate 30.

[0044] Furthermore, the antenna device 1 has directivity in the antenna horizontal direction at the operating frequency. Therefore, when the ground plate 10 is arranged horizontally, the antenna device 1 functions as an antenna having a main beam in the horizontal direction. The antenna horizontal direction here refers to the direction from the center of the opposing conductor plate 30 toward its edge. From another perspective, the antenna horizontal direction refers to the direction perpendicular to the perpendicular line to the ground plate 10 that passes through the center of the opposing conductor plate 30. The antenna horizontal direction corresponds to the lateral direction (in other words, the side) of the antenna device 1.

[0045] The operation of the antenna device 1 when transmitting radio waves and the operation when receiving radio waves are reversible. That is, the antenna device 1 can receive a base-plane vertically polarized wave arriving from the horizontal direction of the antenna.

[0046] [Electric potential of the area surrounded by perimeter 42] As can be seen from the fact that the propagation direction of the above-mentioned vertical electric field is from the short-circuit part 40 toward the edge of the opposing conductor plate 30, the current that has flowed from the opposing conductor plate 30 through the short-circuit part 40 to the ground plate 10 due to the LC parallel resonance flows from the short-circuit part 40 to both sides in the longitudinal direction of the ground plate 10. Therefore, in the opposing conductor plate 30, a current flows in the direction from the edge of the opposing conductor plate 30 toward the short-circuit part 40.

[0047] However, the short-circuiting portion 40 is specifically a plurality of short-circuiting pins 41. The interval between adjacent short-circuiting pins 41 is set so that the current flowing through the opposing conductor plate 30 during LC parallel resonance hardly passes between the short-circuiting pins 41. Therefore, in the opposing conductor plate 30, almost no current flows inside the region surrounded by the periphery 42.

[0048] Fig. 3 is a diagram showing the results of a simulation of the magnitude of the electric field vector generated in the antenna device 1 during LC parallel resonance. It can also be seen from Fig. 3 that during LC parallel resonance, almost no current flows inside the area surrounded by the perimeter 42. Therefore, in the opposing conductor plate 30, the inside of the area surrounded by the perimeter 42 can be used as ground.

[0049] Therefore, in this embodiment, the circuit 50 is disposed in the region surrounded by the periphery 42 of the opposing conductor plate 30. Since the opposing conductor plate 30 is used as the ground of the circuit 50, it is not necessary to expand the ground plate 10 in a direction not facing the opposing conductor plate 30 in order to dispose the circuit 50.

[0050] This makes it possible to prevent the length of the portion of the ground plane 10 through which current flows from approaching the length at which it resonates at the operating frequency, thereby eliminating the need for a strip line for suppressing leakage current from the ground plane 10.

[0051] <Second embodiment> Next, a second embodiment will be described. Fig. 4 shows a plan view of an antenna device 201 of the second embodiment, and Fig. 5 shows a cross-sectional view of the antenna device 201 cut along a plane passing through the straight line Lx and parallel to the XZ plane. Note that the antenna device 201 includes a circuit 50, similar to the antenna device 1, but this is omitted in Figs. 4 and 5.

[0052] The straight line Lx is parallel to the X-axis and passes through the center of the opposing conductor plate 230. The straight line Ly is parallel to the Y-axis and passes through the center of the opposing conductor plate 230. Therefore, the intersection of the straight lines Lx and Ly is the center of the opposing conductor plate 230.

[0053] Support plate 220 and opposing conductor plate 230 included in antenna device 201 are square-shaped in plan view. Also, short-circuiting portion 240 has a configuration in which multiple short-circuiting pins 241 are arranged at positions that pass through a circumference 242. Note that, similar to FIG. 1, for convenience of illustration, only some of the short-circuiting pins 241 are labeled with reference numerals. As shown in FIG. 5, a ground plate 210 is formed below support plate 220. The shape of ground plate 210 in plan view is the same as that of support plate 220.

[0054] In antenna device 201, the tip of cable 2 is connected to antenna device 201 in a region surrounded by short-circuiting portion 240, i.e., a portion where multiple short-circuiting pins 241 are short-circuited to opposing conductor plate 230 and ground plate 210. Almost no current flows in the region surrounded by the portion where short-circuiting portion 240 is shorted. Therefore, by connecting cable 2 to the region surrounded by the portion where short-circuiting portion 240 is shorted, leakage current to cable 2 can be particularly suppressed.

[0055] The diameter R of the shorting pin 241 is 0.4 mm, and the height of the shorting pin 241 is 1.6 mm. The length of P shown in Fig. 4, that is, the diameter of a circle circumscribing the multiple shorting pins 241 arranged on the circumference 242, is 4 mm.

[0056] FIG. 6 shows the rate of inductance change when the length d between adjacent short-circuit pins 241 in antenna device 201 is changed. In FIG. 6, the horizontal axis is the length between adjacent short-circuit pins 241 shown in wavelength ratio. The vertical axis is the rate of inductance change. The rate of inductance change is the rate of inductance change based on the inductance when short-circuiting portion 240 is a single large short-circuiting pin. When short-circuiting portion 240 is a single large short-circuiting pin, it is a single pin with a diameter of 4 mm and a height of 1.6 mm. The inductance of a single pin with a diameter of 4 mm and a height of 1.6 mm is 0.42 nH.

[0057] 6, if the length d between adjacent short-circuiting pins 241 is 0.01 or less in wavelength ratio, the inductance becomes equivalent to when the short-circuiting portion 240 is one large pin. In the case of one short-circuiting pin, current flows on the surface and almost no current flows inside. Therefore, the fact that the inductance becomes equivalent to when the short-circuiting portion 240 is one large pin indicates that almost no current flows in the area surrounded by multiple short-circuiting pins 241.

[0058] From the results of FIG. 6, it can be said that the length d between adjacent short-circuiting pins 241, that is, the distance between the short-circuiting pins 241 adjacent thereto, is preferably 0.01 wavelength or less.

[0059] <Third embodiment> Fig. 7 shows a plan view of an antenna device 301 according to the third embodiment. The antenna device 301 also includes a circuit 50, but this is omitted in Fig. 7. The antenna device 301 includes one cylindrical short-circuit pin 340 as a short-circuiting portion.

[0060] One cylindrical shorting pin 340 can also be considered as a pin with the length d between adjacent shorting pins set to 0. Therefore, almost no current flows in the area surrounded by the shorting pins 340.

[0061] Although the embodiments have been described above, the disclosed technology is not limited to the above-described embodiments, and the following modifications are also included in the scope of the disclosure. Furthermore, in addition to the modifications described below, various modifications can be made without departing from the spirit of the invention.

[0062] <Variation 1> In the opposing conductor plates 30 and 230, the shape of the portion where the short-circuiting portions 40 and 240 are shorted is not limited to the rectangular and circular shapes exemplified in the embodiment. The shape of the portion where the short-circuiting portions 40 and 240 are shorted can be various shapes such as a square or an ellipse. [Explanation of symbols]

[0063] 1: antenna device 2: cable 10: ground plate 20: support plate 30: opposing conductor plate 31: feed point 32: feed pin 40: short circuit portion 41: short circuit pin 42: circumference 50: circuit 201: antenna device 210: ground plate 220: support plate 230: opposing conductor plate 240: short circuit portion 241: short circuit pin 242: circumference 301: antenna device 340: short circuit pin

Claims

1. A ground plate (10, 210) which is a flat conductive member; a counter conductor plate (30, 230) which is a flat conductor member disposed at a predetermined distance from the ground plane and is electrically connected to the power supply line; a short circuit portion (40, 240) provided in a central region of the opposing conductor plate and electrically connecting the opposing conductor plate and the ground plane; an antenna device having an operating frequency that is a frequency at which an inductance of the short circuit portion and a capacitance formed by the ground plate and the opposing conductor plate resonate in parallel, The short-circuit portion has a circumferential portion that is short-circuited with the opposing conductor plate, The antenna device further comprises a circuit (50) disposed in a region surrounded by the short-circuited portion of the opposing conductor plate.

2. 2. The antenna device according to claim 1, The antenna device has a cable (2) connected to an area surrounded by the short-circuited portion of the short-circuited portion.

3. 3. The antenna device according to claim 1, The antenna device, wherein the short-circuiting portion has a plurality of short-circuiting pins (41, 241) that electrically connect the opposing conductor plate and the ground plate, and the portion where the plurality of short-circuiting pins are connected to the opposing conductor plate is located on one of the circumferences.

4. 4. The antenna device according to claim 3, An antenna device, wherein the distance between adjacent shorting pins among the multiple shorting pins is equal to or less than 0.01 times the wavelength corresponding to the operating frequency.

5. 5. The antenna device according to claim 3, An antenna device, wherein the multiple shorting pins are arranged on the circumference of a single rectangle.

6. 5. The antenna device according to claim 3, An antenna device, wherein the multiple shorting pins are arranged on a single circumference.

7. 3. The antenna device according to claim 1, The antenna device includes a single cylindrical short-circuit pin (340) as the short-circuit portion.

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