JP6145785B1 - Antenna device - Google Patents

Abstract

Provided is an antenna device that can be reduced in thickness and size while ensuring a high antenna gain and a good axial ratio. A dielectric layer 4 has a first conductor layer 2 including a loop conductor 21 and four radiating elements 22 on one surface, and the second conductor layer 3 is disposed on the other surface of the dielectric layer 4. Only a two-layer substrate having The loop conductor 21 has an arc shape having an electrical length of approximately one wavelength, and four radiating elements 22 are arranged outside the loop conductor 21 at a predetermined interval, each of which is a loop conductor 21. The radiating elements 22 are rotationally symmetric with respect to the arc central portion of the loop conductor 21. [Selection] Figure 1

Description

  The present invention relates to an antenna device that radiates circularly polarized waves.

  Since an antenna device that radiates circularly polarized waves is resistant to rotational fluctuations toward the receiving terminal, an RFID (Radio Frequency Identifier) system (frequency used: 920 MHz) and Bluetooth (registered trademark) represented by i-Beacon (registered trademark) It is used in a system using Low Energy (operating frequency 2.4 GHz to 2.485 GHz).

For example, in an RFID system, circular polarization is used for the reader / writer and linear polarization is used for the reception tag in order to increase the tolerance depending on the position of the reception tag.
Further, in a system using Bluetooth (registered trademark) Low Energy, a circularly polarized beacon may be used in order to perform stable reception by a receiving terminal using linearly polarized waves such as a smartphone.

  As an antenna device that radiates circularly polarized waves, for example, there are those described in Patent Documents 1 to 3. The antenna device described in Patent Document 1 has a configuration in which a bow-tie-shaped slot is arranged on a loop conductor. The antenna device described in Patent Document 2 has a configuration in which a closed loop is arranged on the outer periphery (same plane) of the loop conductor. The antenna device described in Patent Document 3 has a configuration in which two or more slots are arranged on a loop conductor.

Japanese Patent No. 5323448 Japanese Patent No. 4930947 Japanese Patent No. 4700703

  The generation of circularly polarized waves can be realized with a simple configuration such as cutting out a part of the patch antenna element. On the other hand, in order to obtain a good axial ratio and high antenna gain over a wide band, many antennas are arranged in an array. There is a problem in that it is difficult to reduce the size and thickness of the antenna, and it is necessary to provide the radiation element in a three-dimensional manner with a thickness in the radiation direction of the antenna.

For example, the antenna device described in Patent Document 1 requires a configuration in which elements are arranged in the thickness direction, and thickness is necessary to obtain a high antenna gain.
In the antenna device described in Patent Document 2, the thickness of the antenna at 1.5 GHz is set to 6.4 mm in the embodiment, and the thickness is necessary to obtain a high antenna gain.
Further, the antenna device described in Patent Document 3 requires a configuration in which elements are arranged in the thickness direction.
As described above, it is difficult to reduce the size and thickness of the antenna device described in any of Patent Documents 1 to 3.

  On the other hand, as an antenna device that can be reduced in thickness, for example, there is one shown in a perspective view of FIG. The antenna device 100 shown in the figure is configured to radiate circularly polarized waves by cutting out a part of the patch antenna element 102. The patch antenna element 102 is provided at the center of the surface of the square plate-like dielectric 101, and one of two opposing corner portions (corner portions 102a and 102b shown in the figure) is cut away. The dielectric 101 has a side of 80 mm and a thickness of 1.6 mm, and a conductor is provided on the entire back surface. The patch antenna element 102 is provided with a power supply unit 103. A coaxial cable (not shown) is connected to the power supply unit 103, for example, and power is supplied through the coaxial cable.

  FIG. 17 is a diagram showing the axial ratio (dB) and antenna gain (dBi) of the antenna device 100 shown in FIG. 16, where (a) is the axial ratio and (b) is the antenna gain. Bands Δf (2.4 GHz to 2.5 GHz) shown in (a) and (b) of the figure are Bluetooth (registered trademark) Low Energy bands. Since the antenna device 100 can be realized with a two-layer substrate, the antenna device 100 can be reduced in thickness, but the ratio band of the axis ratio 3 dB or less in the band Δf is narrow, and a favorable axis ratio cannot be obtained. On the other hand, regarding the antenna gain, the right-handed circularly polarized wave CW is higher than the left-handed circularly polarized wave CCW, and is a right-handed circularly polarized antenna.

  It is an object of the present invention to provide an antenna device that can be thinned and miniaturized while ensuring a high antenna gain and a good axial ratio.

  The antenna device of the present invention is a flat antenna device that radiates circularly polarized waves, and includes a first conductor layer that includes a loop conductor and a radiating element made of a conductor, and a second conductor that is substantially entirely made of a conductor. A conductor layer, and a dielectric layer sandwiched between the first conductor layer and the second conductor layer, wherein the loop conductor has an arc shape having an electrical length of approximately one wavelength, One end has a power feeding portion, the other end has a termination portion terminated with a predetermined impedance, and two or more of the radiating elements are arranged outside the loop conductor at a predetermined interval, and the loop conductor The radiating elements are rotationally symmetric with respect to the arc central portion of the loop conductor.

  According to the above configuration, a two-layer substrate having a first conductor layer including a loop conductor and a radiating element on one surface of the dielectric layer and a second conductor layer on the other surface of the dielectric layer is realized. As a result, the thickness and size can be reduced. Further, the loop conductor has an electrical length of approximately one wavelength, and two or more radiating elements are disposed, each having an electrical length of approximately ¼ wavelength, thus ensuring a high antenna gain and a good axial ratio. be able to. Thus, a high antenna gain and a good axial ratio can be ensured, and a reduction in thickness and size can be achieved.

  As one aspect of the antenna device of the present invention, for example, the radiating element is a first radiating element, and the first conductor layer further includes a second radiating element made of a conductor, and the second radiating element is provided. Are arranged at a predetermined interval inside the loop conductor.

  According to the above configuration, the area of the radiating element itself is increased by the newly provided second radiating element, and a higher antenna gain can be obtained.

  As one aspect of the antenna device of the present invention, for example, the second conductor layer is not provided with a conductor at the center corresponding to the arc center of the loop conductor.

  According to the above configuration, the wireless circuit can be provided in a portion where the conductor of the second conductor layer is not provided, and an antenna device incorporating the wireless circuit can be provided.

  As one aspect of the antenna device of the present invention, for example, the radiating element has a substantially fan-like planar shape.

  According to the above configuration, even if the shape of the radiating element is a substantially fan-like planar shape, a high antenna gain and a good axial ratio can be ensured, and a reduction in thickness and size can be achieved.

  As one aspect of the antenna device of the present invention, for example, the radiating element has a substantially rectangular planar shape.

  According to the above configuration, even if the shape of the radiating element is a substantially rectangular planar shape, a high antenna gain and a good axial ratio can be ensured, and a reduction in thickness and size can be achieved.

  The antenna device of the present invention can be reduced in thickness and size while ensuring a high antenna gain and a good axial ratio.

The top view and sectional drawing which show schematic structure of the antenna device which concerns on 1st Embodiment of this invention. The figure which shows the dimension when using the antenna apparatus of FIG. 1 with the system etc. which used Bluetooth (trademark) Low Energy. The figure which shows magnetic field distribution in the antenna surface of the antenna apparatus of FIG. The figure which shows the axial ratio and antenna gain of the antenna apparatus of FIG. The top view which shows schematic structure of the antenna device which concerns on 2nd Embodiment of this invention. Enlarged view of the second radiating element in FIG. The figure which shows the dimension in the center part when using the antenna apparatus of FIG. 5 with the system etc. which used Bluetooth (trademark) Low Energy. The figure which shows the axial ratio and antenna gain of the antenna apparatus of FIG. The top view and sectional drawing which show schematic structure of the antenna device which concerns on 3rd Embodiment of this invention. The top view which shows schematic structure of the 1st modification of the antenna apparatus of FIG. The figure which shows the axial ratio and antenna gain of the antenna apparatus of the 1st modification of FIG. The top view which shows schematic structure of the 2nd modification of the antenna apparatus of FIG. The figure which shows the axial ratio and antenna gain of the antenna apparatus of the 2nd modification of FIG. The top view which shows schematic structure of the 3rd modification of the antenna apparatus of FIG. The figure which shows the axial ratio and antenna gain of the antenna apparatus of the 3rd modification of FIG. A perspective view showing a schematic configuration of a conventional antenna device The figure which shows the axial ratio and antenna gain of the conventional antenna apparatus of FIG.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments for carrying out the invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a plan view and a cross-sectional view showing a schematic configuration of an antenna apparatus 1A according to the first embodiment of the present invention. In this case, (a) in the figure is a plan view on the front side, (b) is a plan view on the back side, and (c) is a cross-sectional view along the line AA.

  An antenna device 1A according to the present embodiment is a flat antenna device that radiates circularly polarized waves, and includes a first conductor layer 2 including a loop conductor 21 and a radiating element 22 made of a conductor, and a substantially entire surface being a conductor. And a dielectric layer 4 sandwiched between the first conductor layer 2 and the second conductor layer 3. The loop conductor 21 has an arc shape having an electrical length of approximately one wavelength, has a power feeding portion 211 (see FIG. 1C) at one end, and is terminated at a predetermined impedance at the other end. Part 212 (see FIG. 1C).

  The power feeding unit 211 is inserted into a through hole of the dielectric layer 4 formed immediately below one end of the loop conductor 21, and one end is connected to one end of the loop conductor 21 and the other end of the conducting wire 211a. Terminal 211b. Power is supplied to the power supply unit 211 via, for example, a coaxial cable (not shown). The end portion 212 is inserted into a through-hole in the dielectric layer 4 that is opened directly below the other end of the loop conductor 21, and has one end connected to the other end of the loop conductor 21, and the other end of the conductor 212 a. A predetermined impedance element (for example, a resistance element of 50Ω) 212b interposed between the second conductor layer 3 and the second conductor layer 3 is formed.

  The radiating element 22 has a substantially fan-like planar shape, and four radiating elements 22 are arranged outside the loop conductor 21 with a predetermined interval. Each radiating element 22 has an electrical length of approximately ¼ wavelength outward from the center of the arc of the loop conductor 21 and operates with linearly polarized waves. The radiating elements 22 are rotationally symmetric with respect to the center of the arc of the loop conductor 21. The material of the conductor forming the loop conductor 21 and the four radiating elements 22 and the conductor forming the second conductor layer 3 is, for example, copper. The material of the dielectric layer 4 is, for example, glass epoxy (NEMA standard: FR-4). NEMA is an abbreviation for National Electrical Manufacturers Association.

  FIG. 2 is a diagram showing dimensions when the antenna device 1A according to the present embodiment is used in a system or the like using Bluetooth (registered trademark) Low Energy (operating frequency 2.4 GHz to 2.485 GHz). (A) of the figure shows the whole antenna device 1A, and (b) shows the central portion of the antenna device 1A. As shown in FIGS. 5A and 5B, the overall diameter of the antenna device 1A is 80 mm, the distance from one of the opposing radiating elements 22 to the other is 53.9 mm, and the width of each radiating element 22 is 16 mm. The arc of each radiating element 22 is 75 degrees, the line between the loop conductor 21 and the radiating element 22 is 0.5 mm, the distance between the open ends of the loop conductor 21 is 2.7 mm, and the gap between the radiating elements 22 is 15 degrees. The total thickness of the apparatus 1A is 1.6 mm (not shown). The overall diameter of the antenna device 1A is related to the FB ratio (Front to Back Ratio). Further, as described above, the loop conductor 21 operates with substantially one wavelength for one turn. Further, the radiating element 22 operates at approximately a quarter wavelength as described above. Further, by changing the line between the loop conductor 21 and the radiating element 22, the amount of power distributed to the radiating element 22 changes.

  FIG. 3 is a diagram showing a magnetic field distribution on the antenna surface of the antenna device 1A according to the present embodiment. In the figure, among the four radiating elements 22, the phase of the radiating element 22-1 closest to the power feeding unit 211 is displayed as 0 degree, and the phases of the other radiating elements 22-2 to 22-4 are clocked. Around 90, 180 and 270 degrees are displayed. An arrow 30 indicated by a dotted line in the figure indicates a magnetic field component. The loop conductor 21 operates with an electrical length of 360 degrees per round. The radiating element 22-1 located on the outer periphery of the loop conductor 21 is capacitively coupled to the loop conductor 21 as indicated by reference numeral 31 in the figure. The magnetic field component on the loop conductor 21 is also generated in the other radiating elements 22-2 to 22-4 that are continuously located on the outer periphery. The loop conductor 21 operates as a microstrip line.

  Electromagnetic waves are radiated when the radiating elements 22-1 to 22-4 arranged on the outer periphery of the loop conductor 21 are sequentially excited clockwise (in the direction indicated by the arrow 32 in the figure). The electromagnetic waves radiated at this time are left-handed circularly polarized waves. In addition, since the radiation direction of electromagnetic waves is basically viewed from the back side of the antenna device 1A, it becomes a left-handed circularly polarized wave. If the power feeding section 211 and the terminal section 212 are reversed, the radiating elements 22-1 to 22-4 are excited in the counterclockwise order (in the direction opposite to the direction indicated by the arrow 32 in the figure), so that the right-handed circularly polarized wave It becomes.

  FIG. 4 is a diagram showing an axial ratio (dB) and an antenna gain (dBi) of the antenna device 1A according to the present embodiment, where (a) in FIG. 4 is an axial ratio and (b) is an antenna gain. Bands Δf (2.4 GHz to 2.5 GHz) shown in (a) and (b) of the figure are Bluetooth (registered trademark) Low Energy bands. As can be seen from the figure, the antenna device 1A according to the present embodiment can obtain a high antenna gain and a good axial ratio in the Δf band. Compared with the axial ratio of the conventional antenna device 100 shown in FIG. 17, the antenna device 1A according to the present embodiment has a wider bandwidth than the axial ratio of 3 dB. Further, compared with the antenna gain of the conventional antenna device 100, the difference between the antenna gain in the left-handed circularly polarized wave CCW and the antenna gain in the right-handed circularly polarized wave CW is larger. The larger this difference, the better and the lower the axial ratio value. In the conventional antenna device 100, the axial ratio is about 1 dB lower than 3 dB, whereas in the antenna device 1A according to the present embodiment, the axial ratio is about 2 dB lower than 3 dB. Obviously, the antenna device 1A according to the present embodiment has a better axial ratio.

  The antenna device 1 </ b> A according to the present embodiment has the first conductor layer 2 including the loop conductor 21 and the four radiating elements 22 on one surface of the dielectric layer 4, and the other of the dielectric layers 4. Since it can be constituted by only a two-layer substrate having a thickness of 1.6 mm having the second conductor layer 3 on the surface, it is possible to reduce the thickness and size. A substrate having a conductor pattern on both sides is called a double-sided substrate or a two-layer substrate.

  As described above, the antenna device 1A according to the present embodiment has the first conductor layer 2 including the loop conductor 21 and the four radiating elements 22 on one surface of the dielectric layer 4, and the dielectric layer. Since it is composed of only a two-layer substrate having the second conductor layer 3 on the other surface of 4, the thickness and size can be reduced. In addition, the loop conductor 21 has an arc shape having an electrical length of approximately one wavelength, and four radiating elements 22 are arranged outside the loop conductor at a predetermined interval. Since the electrical length is approximately ¼ wavelength outward from the center of the arc and the radiating elements 22 are rotationally symmetric with respect to the center of the arc of the loop conductor 21, a high antenna gain and a good axial ratio are ensured. can do.

(Second Embodiment)
FIG. 5 is a plan view showing a schematic configuration of an antenna apparatus 1B according to the second embodiment of the present invention. In this case, (a) in the figure is a plan view on the front side, and (b) is a plan view on the back side. The AA line sectional view is the same as the AA line sectional view of the antenna device 1A according to the first embodiment shown in FIG. In FIG. 5, members that are the same as those in the antenna device 1 </ b> A according to the first embodiment described above are denoted by the same reference numerals.

  As shown in FIG. 5, the antenna device 1B according to the present embodiment has a second radiating element 23 made of a conductor, in addition to having the same configuration as the antenna device 1A according to the first embodiment. The second radiating element 23 is included in the first conductor layer 2 and is arranged inside the loop conductor 21 with a predetermined interval. FIG. 6 is an enlarged view of the second radiating element 23 in FIG. In the same figure, the second radiating element 23 is integrated with the cross-shaped portion 23-1 and each of the four tips of the cross-shaped portion 23-1, and is an arc-shaped piece along the inside of the loop conductor 21. It is comprised from the part 23-2. The interval between the adjacent small piece portions 23-2 is substantially the same as the interval between the open ends of the loop conductor 21. Since the second radiating element 23 is included in the first conductor layer 2 together with the radiating element 22, the radiating element 22 is referred to as the first radiating element 22 with respect to the second radiating element 23.

  FIG. 7 is a diagram illustrating dimensions at the center when the antenna device 1B according to the present embodiment is used in a system using Bluetooth (registered trademark) Low Energy. The dimensions of the antenna device 1B other than the central portion are the same as those of the antenna device 1A according to the first embodiment. As shown in the figure, the diameter of the second radiating element 23 is 17.4 mm, the total length is 31.4 mm, the line width is 1 mm, the arc of the small piece portion 23-2 of the second radiating element 23 is 75 degrees, the loop The distance between the conductor 21 and the conductor 21 is 0.5 mm. By setting the total length of the second radiating element 23 to 31.4 mm, the second radiating element 23 operates at approximately ½ wavelength. Moreover, the electric power distributed to the 2nd radiation | emission element 23 changes by changing the space | interval with the loop conductor 21. FIG.

  FIG. 8 is a diagram illustrating the axial ratio (dB) and the antenna gain (dBi) of the antenna device 1B according to the present embodiment, where (a) in FIG. 8 is the axial ratio and (b) is the antenna gain. Bands Δf (2.4 GHz to 2.5 GHz) shown in (a) and (b) of the figure are Bluetooth (registered trademark) Low Energy bands. As can be seen from the figure, the antenna device 1B according to the present embodiment can obtain a high antenna gain and a good axial ratio in the Δf band. In particular, the antenna gain is about 2.4 dB higher in the 2.4 GHz band than the antenna device 1A according to the first embodiment. Further, the difference between the antenna gain in the left-handed circularly polarized wave CCW and the antenna gain in the right-handed circularly polarized wave CW is also large as in the antenna device 1A according to the first embodiment.

  Thus, by providing the second radiating element 23 in addition to the first radiating element 22, the area of the radiating element itself is increased, and 2.4 GHz compared to the antenna device 1A according to the first embodiment. A higher antenna gain is obtained in the band. Further, since it can be realized by a two-layer substrate having a thickness of 1.6 mm, the thickness and size can be reduced.

(Third embodiment)
FIG. 9 is a plan view and a cross-sectional view showing a schematic configuration of an antenna apparatus 1C according to the third embodiment of the present invention. In this case, (a) in the figure is a plan view on the front side, (b) is a plan view on the back side, and (c) is a cross-sectional view along the line AA. In the figure, members common to the antenna device 1A according to the first embodiment are denoted by the same reference numerals.

  As shown in FIG. 9, the antenna device 1C according to the present embodiment has the same configuration as the antenna device 1A according to the first embodiment, but has a wireless circuit 26, and the back surface of the antenna device 1C. The difference is that no conductor is provided at the center of the second conductor layer 3 provided on the side, that is, at the center corresponding to the arc center of the loop conductor 21. A portion of the second conductor layer 3 having no conductor is referred to as a blank portion 25, and the wireless circuit 26 is disposed in the blank portion 25.

  The radio circuit 26 is connected to the other end of the conducting wire 211 a of the power feeding unit 211, that is, the end on the second conductor layer 3 side. One end of the conducting wire 211a of the power feeding unit 211 is connected to one end of the loop conductor 21 as in the antenna device 1A according to the first embodiment. Similarly to the antenna device 1A according to the first embodiment, one end of the conducting wire 212a is connected to the other end of the loop conductor 21 and the other end of the conducting wire 212a is a predetermined impedance element (for example, a 50Ω resistance element). ) It is connected to the second conductor layer 3 through 212b. The wireless circuit 26 is, for example, a Bluetooth (registered trademark) IC (Integrated Circuit) and a set of peripheral circuit components and signal wirings necessary for the operation of the IC. Power is supplied from the wireless circuit 26 to the power supply unit 211.

  Thus, by providing the blank portion 25 without a conductor at the center of the second conductor layer 3, the radio circuit 26 can be provided in the blank portion 25, and an antenna device incorporating the radio circuit 26 is provided. can do.

  Although the antenna devices 1A to 1C according to the first to third embodiments described above have the four radiating elements 22, the number of the radiating elements 22 is not limited and may be two or more. Moreover, although the shape of the radiation element 22 is a substantially fan-like planar shape, it may be a substantially rectangular planar shape, for example. Hereinafter, modified examples of the antenna device 1A according to the first embodiment will be described.

(First modification of the first embodiment)
FIG. 10 is a plan view showing a schematic configuration of a first modification of the antenna device 1A according to the first embodiment. As shown in the figure, the antenna device 1D of the first modified example has eight radiating elements 22. The shape of each radiating element 22 is a substantially fan-like planar shape that is the same as that of the antenna device 1A according to the first embodiment.

  FIG. 11 is a diagram illustrating the axial ratio (dB) and the antenna gain (dBi) of the antenna device 1D of the first modified example, where (a) in FIG. 11 is the axial ratio and (b) is the antenna gain. Bands Δf (2.4 GHz to 2.5 GHz) shown in (a) and (b) of the figure are Bluetooth (registered trademark) Low Energy bands. As can be seen from the figure, the antenna device 1D according to the first modification is wider than the antenna device 1A according to the first embodiment because the number of the radiating elements 22 is larger than that of the antenna device 1A according to the first embodiment. Good axial ratio can be obtained in the band. Further, the antenna gain varies little for both the left-handed circularly polarized wave CCW and the right-handed circularly polarized wave CW, and a more beautiful circularly polarized wave can be obtained from the antenna device 1A according to the first embodiment. Further, since it can be realized by a two-layer substrate having a thickness of 1.6 mm, the thickness and size can be reduced.

(Second modification of the first embodiment)
FIG. 12 is a plan view showing a schematic configuration of a second modification of the antenna device 1A according to the first embodiment. As shown in the figure, the antenna device 1E of the second modification has three radiating elements 22. The shape of each radiating element 22 is a substantially fan-like planar shape that is the same as that of the antenna device 1A according to the first embodiment.

  FIG. 13 is a diagram illustrating the axial ratio (dB) and the antenna gain (dBi) of the antenna device 1E of the second modified example, in which (a) is the axial ratio and (b) is the antenna gain. Bands Δf (2.4 GHz to 2.5 GHz) shown in (a) and (b) of the figure are Bluetooth (registered trademark) Low Energy bands. As can be seen from the figure, the antenna device 1E of the second modification can obtain a good axial ratio and antenna gain in the Δf band. The performance is almost the same as the antenna device 1A according to the first embodiment. Further, since it can be realized by a two-layer substrate having a thickness of 1.6 mm, the thickness and size can be reduced.

(Third Modification of First Embodiment)
FIG. 14 is a plan view showing a schematic configuration of a third modification of the antenna device 1A according to the first embodiment. As shown in the figure, the antenna device 1F of the third modification has five radiating elements 22A. The shape of each radiation element 22A is different from that of the antenna device 1A according to the first embodiment, and has a substantially rectangular planar shape.

  FIG. 15 is a diagram illustrating the axial ratio (dB) and the antenna gain (dBi) of the antenna device 1F according to the third modified example, in which (a) is the axial ratio and (b) is the antenna gain. Bands Δf (2.4 GHz to 2.5 GHz) shown in (a) and (b) of the figure are Bluetooth (registered trademark) Low Energy bands. As can be seen from the figure, the antenna device 1F of the third modification can obtain a good axial ratio and antenna gain in the Δf band. The performance is almost the same as the antenna device 1A according to the first embodiment. Further, since it can be realized by a two-layer substrate having a thickness of 1.6 mm, the thickness and size can be reduced.

The modification example of the antenna device 1A according to the first embodiment has been described above by way of example.
Needless to say, the first to third modifications can also be applied to the antenna devices 1B and 1C according to the second and third embodiments.

  As described above, the first to third embodiments of the present invention and the first to third modifications of the first embodiment have been described in detail, but various changes and modifications are made without departing from the spirit and scope of the present invention. It will be apparent to those skilled in the art that this is possible.

  The antenna device according to the present invention can be applied to an RFID system, a system using Bluetooth (registered trademark) Low Energy, or the like.

1A to 1F Antenna device 2 First conductor layer 3 Second conductor layer 4 Dielectric layer 21 Loop conductor 22, 22-1 to 22-4, 22A Radiating element (first radiating element)
23 Second radiating element 25 Blank part 26 Radio circuit 211 Feeding part 212 Terminating part 212b Impedance element

Claims (5)

A flat antenna device that radiates circularly polarized waves,
A first conductor layer including a loop conductor and a radiating element made of a conductor;
A second conductor layer substantially entirely made of a conductor;
A dielectric layer sandwiched between the first conductor layer and the second conductor layer,
The loop conductor has an arc shape having an electrical length of approximately one wavelength, has a power feeding portion at one end, and has a termination portion terminated with a predetermined impedance at the other end,
Two or more radiating elements are arranged outside the loop conductor at a predetermined interval, and have an electrical length of about ¼ wavelength outward from the center of the arc of the loop conductor, thereby allowing linearly polarized light. Work,
The antenna device according to claim 1, wherein the radiating elements are rotationally symmetric with respect to a circular arc center portion of the loop conductor. The antenna device according to claim 1,
The radiating element is a first radiating element;
The first conductor layer further includes a second radiating element made of a conductor,
The antenna device according to claim 1, wherein the second radiating elements are arranged at a predetermined interval inside the loop conductor. The antenna device according to claim 1,
The antenna device, wherein the second conductor layer is not provided with a conductor in a central portion corresponding to a circular arc central portion of the loop conductor. The antenna device according to any one of claims 1 to 3,
The antenna device, wherein the radiating element has a substantially fan-like planar shape. The antenna device according to any one of claims 1 to 3,
The antenna device, wherein the radiating element has a substantially rectangular planar shape.

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