Loop antenna transmission / reception system and loop antenna device

Abstract

To allow one-to-other orbital angular momentum (OAM) multiplexing communication to be performed.SOLUTION: A loop antenna transmission / reception system includes: a first loop antenna device 100 having a plurality of circular loop antennas, each with a perimeter length that is approximately an integer multiple of a wavelength, arranged concentrically on the same plane; a first reflecting member 101 arranged on the rear side of the first loop antenna device; and a second loop antenna device 200 having the same configuration as the first loop antenna device, in which in the relation with the first loop antenna device 101, their front sides are arranged facing each other in the state where their central axes are aligned with each other. Furthermore, a third loop antenna device 300 is arranged adjacent to the first loop antenna device 100, and the loop antenna transmission / reception system is adapted to also perform wireless communication with another loop antenna device (fourth loop antenna device 400).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a loop antenna transmission / reception system and a loop antenna device, and more particularly to a loop antenna transmission / reception system and a loop antenna device that are applied to those performing OAM communication. [Background technology]

[0002] In recent years, OAM (Orbital Angular Momentum) multiplexing has been proposed as a method of multiplexing wireless communication at the same frequency. This method utilizes the phenomenon in which interactions are permitted only when the orbital angular momentum of the electromagnetic field is conserved, and transmits orbital angular momentum (OAM) information in electromagnetic waves. In waves such as lasers, whose beam cross section is a Gaussian distribution system, the phase space distribution in the cross section with respect to the direction φ is constant for normal waves. On the other hand, in OAM waves, the phase space distribution changes linearly with respect to the direction φ according to exp(jmφ) (where m is the mode order of the OAM wave and is called the magnetic quantum number), and the same phase surface advances in a spiral shape. In the case of optical communications, such OAM waves can be realized relatively easily by using a laser and a hologram or a spiral phase plate. However, in the case of microwaves, it is not easy to realize OAM waves because the methods of transmitting and receiving eigenmodes and the methods of transmitting narrowed beams are significantly different from those in optical communications.

[0003] Patent Document 1 describes a wireless communication device that performs OAM multiplex communication. The transmitting antenna and the receiving antenna described in Patent Document 1 each have a different perimeter length that is approximately an integral multiple of a wavelength determined by a wireless communication frequency, and each antenna includes a plurality of circular loop antennas arranged concentrically on the same plane, and a plurality of power feeders that are individually connected to the plurality of circular loop antennas. The central axes of the plurality of circular loop antennas of the transmitting antenna and the central axes of the plurality of circular loop antennas of the receiving antenna are arranged in a substantially straight line.

[0004] According to the wireless communication device described in Patent Document 1, OAM waves are realized using a circular loop antenna device which has a simple structure, is inexpensive, and is easy to mass-produce, thereby making it possible to realize wireless communication with an improved transmission rate per frequency. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2017 / 188172 Summary of the Invention [Problem to be solved by the invention]

[0006] By the way, the OAM multiplex communication proposed so far is one-to-one communication in which one circular loop antenna faces another circular loop antenna. However, in order to improve communication efficiency, it is desired to be able to perform one-to-other OAM multiplex communication.

[0007] An object of the present invention is to provide a loop antenna transmission / reception system and a loop antenna device capable of one-to-other OAM multiplex communication. [Means for solving the problem]

[0008] The loop antenna transmission / reception system of the present invention comprises a first loop antenna device having a plurality of circular loop antennas arranged concentrically on the same plane, each having a perimeter that is approximately an integer multiple of the wavelength determined by the wireless communication frequency, a first reflecting member arranged on the rear side of the first loop antenna device, a second loop antenna device having the same configuration as the first loop antenna device and arranged with their front sides facing each other with their central axes aligned between the first loop antenna device, a second reflecting member arranged on the rear side of the second loop antenna device, a third loop antenna device arranged in an adjacent position on the same plane as the first loop antenna device, each having a perimeter that is approximately an integer multiple of the wavelength determined by the wireless communication frequency, a third reflecting member arranged at a position away from the second reflecting member, and a fourth loop antenna device having the same configuration as the third loop antenna device and having the third reflecting member arranged on its rear side. Wireless communication is performed between the first and second loop antenna devices, which are arranged opposite each other with their respective central axes aligned, and wireless communication is also performed between the third and fourth loop antenna devices via a communication path that is reflected by the first and third reflecting members.

[0009] In addition, the loop antenna device of the present invention is a loop antenna device in which a plurality of circular loop antennas, each having a peripheral length that is approximately an integer multiple of the wavelength determined by the wireless communication frequency, are arranged concentrically on the same plane, and a varactor diode whose characteristics change when turned on and off is loaded in at least a portion of the positions where the current determined by the wireless communication frequency is maximum in the plurality of circular loop antennas. Effect of the Invention

[0010] According to the loop antenna transmission / reception system of the present invention, OAM multiplex communication can be performed between the first loop antenna device and the second loop antenna device, and OAM multiplex communication can be performed between the third loop antenna device and the fourth loop antenna device. Since the first loop antenna device and the third loop antenna device are arranged in close proximity to the front surface of the first reflecting member, one-to-many OAM communication can be performed.

[0011] Furthermore, according to the loop antenna device of the present invention, when the varactor diode is turned on, interference from other loop antenna devices placed nearby can be reduced, resulting in a loop antenna device suitable for one-to-many OAM multiplex communication. [Brief description of the drawings]

[0012] [Figure 1] 1 is a configuration diagram showing an example of an outline of an OAM multiplex communication system according to an embodiment of the present invention. [Diagram 2] 1 is a configuration diagram showing an example of a transmission-side loop antenna and a reception-side loop antenna according to an embodiment of the present invention; [Diagram 3] 1 is a plan view showing an example of a surface of a loop antenna according to an embodiment of the present invention; [Figure 4] 1 is a cross-sectional view showing an example of a cross-sectional configuration of a loop antenna according to an embodiment of the present invention. [Diagram 5] FIG. 4 is a diagram showing an example of a maximum current point of a loop antenna according to an embodiment of the present invention. [Figure 6] 5A and 5B are diagrams illustrating an example of pass characteristics of a diode according to an embodiment of the present invention when the diode is on and when the diode is off. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention (hereinafter referred to as "this embodiment") will be described with reference to the accompanying drawings. [System Configuration] FIG. 1 is a diagram showing the configuration of a loop antenna transmission / reception system to which the OAM multiplex communication of this embodiment is applied. As shown in FIG. 1, the system of this example includes a first loop antenna device 100, a second loop antenna device 200, a third loop antenna device 300, and a fourth loop antenna device 400.

[0014] Each of the loop antenna devices 100, 200, 300, and 400 has a plurality of circular loop antennas arranged concentrically on the same plane, each of which has a perimeter that is an integral multiple of the wavelength determined by the wireless communication frequency, in order to perform OAM multiplex communication. The detailed configuration of each of the loop antenna devices 100, 200, 300, and 400 will be described in FIG. 2 and subsequent figures.

[0015] The first loop antenna device 100 and the second loop antenna device 200 are arranged with their front sides facing each other with their central axes aligned. A reflecting member (first reflecting member) 101 is arranged on the rear side of the first loop antenna device 100, and a reflecting member (second reflecting member) 201 is arranged on the rear side of the second loop antenna device 200.

[0016] Each of the reflecting members 101, 201 has the same paraboloid shape and functions as a parabolic antenna. That is, the central axis of the circular loop antenna arranged concentrically in the loop antenna devices 100, 200 coincides with the central point of the paraboloid-shaped reflecting members 101, 201, so that radio waves from one loop antenna device are reflected and travel straight to the other loop antenna device. By arranging the paraboloid reflective members 101 and 201 in this manner, an effect is achieved in that the wireless transmission distance between the first loop antenna device 100 and the second loop antenna device 200 can be increased.

[0017] A transmitting / receiving unit 150 is connected to the first loop antenna device 100, and a transmitting / receiving unit 250 is connected to the second loop antenna device 200. As a result, a signal supplied from the transmitting / receiving unit 150 to the first loop antenna device 100 is wirelessly transmitted and received and processed by the transmitting / receiving unit 250 connected to the second loop antenna device 200. In addition, a signal transmitted from the second loop antenna device 200 can also be received and processed by the transmitting / receiving unit 150 connected to the first loop antenna device 100, allowing wireless communication to be performed in both directions. The first loop antenna device 100 is also provided with a voltage application section 160, which selectively supplies a voltage generated by the voltage application section 160 to the circular loop antenna via the transmitting / receiving section 150.

[0018] In this example, the third loop antenna device 300 is arranged on the same plane adjacent to the first loop antenna device 100. The third loop antenna device 300 also has a plurality of circular loop antennas arranged concentrically, similar to the first loop antenna device 100. However, the number of circular loop antennas arranged in the third loop antenna device 300 does not have to be the same as that of the first loop antenna device 100.

[0019] 1, a reflecting member (third reflecting member) 401 is disposed at a position where radio waves from the third loop antenna device 300 reach the position where they are reflected by the reflecting member 101, and a fourth loop antenna device 400 is disposed near the reflecting member 401 (on the front side of the reflecting surface). The fourth loop antenna device 400 has the same configuration as the third loop antenna device 300. 1, the positional relationship between the reflecting member 101 and the third loop antenna device 300 and the positional relationship between the reflecting member 401 and the fourth loop antenna device 400 are set to be point symmetric, so that radio waves from the third loop antenna device 300 are beamformed by the reflecting member 101 and the reflecting member 401 and are received by the fourth loop antenna device 400. When the reflecting member 101 has a paraboloid shape as shown in FIG. 1, the reflecting member 401 also has a similar paraboloid shape.

[0020] A transmitting / receiving unit 350 is connected to the third loop antenna device 300, and a transmitting / receiving unit 450 is connected to the fourth loop antenna device 400. As a result, a signal supplied from the transmitting / receiving unit 350 to the third loop antenna device 300 is wirelessly transmitted and received and processed by the transmitting / receiving unit 450 connected to the fourth loop antenna device 400. In addition, a signal transmitted from the fourth loop antenna device 400 can also be received and processed by the transmitting / receiving unit 350 connected to the third loop antenna device 300, allowing wireless communication to be performed in both directions. The third loop antenna device 300 is also provided with a voltage application section 360 , which selectively supplies a voltage generated by the voltage application section 360 to the circular loop antenna via the transmitting / receiving section 350 . In the system of this embodiment, transmission and reception using the first loop antenna device 100 and the third loop antenna device 300 are not performed simultaneously, but are selectively performed using only one of them.

[0021] [Configuration of loop antenna device] Fig. 2 shows an example of the configuration of the loop antenna devices 100 and 200 of this example. Fig. 2 shows the configurations of the first loop antenna device 100 and the second loop antenna device 200, but the configurations of the third loop antenna device 300 and the fourth loop antenna device 400 are also similar except for the positional relationship with the reflecting member. However, the number (order) of the circular loop antennas of the first and second loop antenna devices 100 and 200 and the number (order) of the circular loop antennas of the third and fourth loop antenna devices 300 and 400 do not have to be the same.

[0022] The first loop antenna device 100 and the second loop antenna device 200 include multiple (four here) circular loop antennas 110-140, 210-240, and perform primary (mode 1), tertiary (mode 3), quintic (mode 5), and seventh-order (mode 7) OAM multiplex communication.

[0023] That is, the first loop antenna device 100 includes four circular loop antennas 110, 120, 130, and 140 and a reflecting member 101. The four circular loop antennas 110, 120, 130, and 140 are arranged at a central position c 1 are arranged in the same plane with their ends aligned. The four circular loop antennas 110 to 140 are arranged at the center position c 1 From the side closest to the center, there are a primary (mode 1) circular loop antenna 110, a tertiary (mode 3) circular loop antenna 120, a quintic (mode 5) circular loop antenna 130, and a quintic (mode 7) circular loop antenna 140.

[0024] The second loop antenna device 200 also includes four circular loop antennas 210, 220, 230, and 240 and a reflecting member 201. The four circular loop antennas 210, 220, 230, and 240 are arranged at the central position c 2 are arranged in the same plane with their ends aligned. The four circular loop antennas 210 to 240 are also located at the center positions c 1 From the side closest to the center, there are a primary (mode 1) circular loop antenna 210, a tertiary (mode 3) circular loop antenna 220, a quinary (mode 5) circular loop antenna 230, and a quinary (mode 7) circular loop antenna 240. Each of the circular loop antennas 110 to 140 and 210 to 240 is formed of a circular conductor that is interrupted at a power feeding portion, and the conductor is not connected in a ring shape. In the example of Fig. 2, circular loop antennas of modes 1, 3, 5, and 7 are arranged concentrically, but this mode arrangement of antennas is only an example, and circular loop antennas of other modes may be arranged concentrically. For example, an antenna of mode 1 (primary), an antenna of mode 2 (secondary), an antenna of mode 3 (tertiary), and an antenna of mode 4 (quaternary) may be arranged concentrically.

[0025] Each of the circular loop antennas 110-140, 210-240 constituting the first loop antenna device 100 and the second loop antenna device 200 is independent of the other, and has a length that is approximately an integer multiple of a wavelength determined by a frequency for wireless transmission in the wireless communication device of this example. In other words, if the length of the primary circular loop antennas 110, 210 is taken as a reference (1x), the tertiary circular loop antennas 120, 220 are approximately three times as long, the quintic circular loop antennas 130, 230 are approximately five times as long, and the seventh order circular loop antennas 140, 240 are approximately seven times as long. The communication performed by the primary circular loop antenna 110 is referred to as mode 1, the communication performed by the tertiary circular loop antenna 120 is referred to as mode 3, the communication performed by the quintic circular loop antenna 130 is referred to as mode 5, and the communication performed by the seventh order circular loop antenna 140 is referred to as mode 7.

[0026] As shown in FIG. 2, the center position c of the first loop antenna device 100 1 The central axis φ is extended in a direction perpendicular to the circular loop antennas 110 to 140. 0 is the center position c of the second loop antenna device 200. 2 That is, the first loop antenna device 100 and the second loop antenna device 200 pass through their respective central axes φ 0 are arranged so that they are almost in agreement.

[0027] In addition, the orientation of terminals (power feed parts) 111, 211 of loop antennas 110, 210 was set to 0°, the orientation of terminals (power feed parts) 121, 221 of loop antennas 120, 220 was set to 90°, the orientation of terminals (power feed parts) 131, 231 of loop antennas 130, 230 was set to 0°, and the orientation of terminals (power feed parts) 141, 241 of loop antennas 140, 240 was set to 90°.

[0028] To explain the signal processing configuration connected to the first loop antenna device 100, for example, a transmission / reception data processing unit 159 generates four transmission data sequences, and the four generated transmission data sequences are supplied to four transmission / reception units 151, 152, 153, and 154. The transmission / reception unit 150 shown in FIG. 1 collectively illustrates these four transmission / reception units 151 to 154. Each of the transmitter / receivers 151 to 154 converts the supplied transmission data sequence into a transmission signal modulated to the same transmission frequency. The transmission signals obtained by each of the transmitter / receivers 151 to 154 are supplied via signal lines 155, 156, 157, and 158 to power feeds 111, 121, 131, and 141 that are connected perpendicularly to the four circular loop antennas 110, 120, 130, and 140. The four circular loop antennas 110, 120, 130, and 140 wirelessly transmit the transmission signals obtained at the power feeding sections 111, 121, 131, and 141, respectively.

[0029] The mode ratio of the OAM wave radiated from a loop antenna is the ratio of the expansion coefficients when the current distribution on the loop antenna is expanded into a Fourier series. The value of this expansion coefficient is determined by the loop radius, the loop conductor width, and the relative positions of each loop, so by designing with appropriate parameters, it is possible to design a loop antenna that can maximize the radiation of OAM waves in any mode.

[0030] Signals wirelessly transmitted from the four circular loop antennas 110, 120, 130, 140 of the first loop antenna device 100 are individually received by the four circular loop antennas 210, 220, 230, 240 of the second loop antenna device 200. The four circular loop antennas 210, 220, 230, 240 each include a separate power supply unit 211, 221, 231, 241, and the received signals obtained at each power supply unit 211, 221, 231, 241 are supplied to four individual transceivers 251, 252, 253, 254 via signal lines 255, 256, 257, 258. Each transceiver 251, 252, 253, 254 receives and processes the signals transmitted at the same frequency to obtain a received data sequence. The received data series obtained in each of the transmitting / receiving sections 251 , 252 , 253 , and 254 are supplied to a transmitting / receiving data processing section 259 .

[0031] When transmitting from the second loop antenna device 200 to the first loop antenna device 100, the transmission process from the first loop antenna device 100 to the second loop antenna device 200 is performed in the reverse flow. Although not shown in Figure 2, wireless transmission between the third loop antenna device 300 and the fourth loop antenna device 400 is performed in the same manner as wireless transmission between the first loop antenna device 100 and the second loop antenna device 200. In this way, the loop antenna transmitting and receiving system of this embodiment enables one-to-many wireless transmission.

[0032] Here, in the four circular loop antennas 110, 120, 130, 140 of the first loop antenna device 100 of this example, varactor diodes, which are variable capacitance diodes, are loaded at the angle positions (angle points) where the current density distribution of the antennas is maximized. Similarly, in each circular loop antenna of the third loop antenna device 300 arranged adjacent to the first loop antenna device 100, a varactor diode is loaded at the angle position where the current density distribution of the antennas is maximized. Details of the angle positions where the current density distribution of the antennas is maximized will be described later.

[0033] The voltage application unit 160 provided in the first loop antenna device 100 applies a voltage to each of the circular loop antennas 110, 120, 130, and 140 of the first loop antenna device 100. However, the voltage application unit 160 turns on the voltage application when the first loop antenna device 100 is not used for transmission or reception, and turns off the voltage application when the first loop antenna device 100 is used for transmission or reception. This on / off switching of the voltage application is performed to change the characteristics of the varactor diodes connected to the circular loop antennas 110, 120, 130, and 140, and when a voltage is applied, it acts to suppress interference with the third loop antenna device 300 located close to the first loop antenna device 100.

[0034] 1 applies a voltage to each circular loop antenna of the third loop antenna device 300, and turns on the voltage application when transmission or reception is not performed using the third loop antenna device 300, and turns off the voltage application when transmission or reception is performed using the third loop antenna device 300. As a result, when a voltage is applied, it acts to suppress interference with the first loop antenna device 100 located close to the third loop antenna device 300.

[0035] [Circular loop antenna loaded with varactor diodes] 1, when the first loop antenna device 100 and the third loop antenna device 300 are arranged close to each other on almost the same plane, the loop antennas having the same circumferential length are close to each other, which causes crosstalk Sx due to interference. In order to suppress the crosstalk Sx due to interference, in this example, a varactor diode is loaded on the circular loop antenna.

[0036] 3 shows in plan view the detailed configuration of the circular loop antennas 110, 120, 130, and 140 arranged in the first loop antenna device 100. The third loop antenna device 300 also has the same configuration as the first loop antenna device 100 when the number of modes is the same. Four circular loop antennas 110, 120, 130, and 140 shown in FIG. 3 are respectively first-order, third-order, fifth-order, and seventh-order loop antennas for OAM waves for OAM multiplex communication. The four circular loop antennas 110, 120, 130, and 140 are disposed on one substrate (first substrate 102).

[0037] In the primary (mode 1) circular loop antenna 110, one varactor diode 110d is disposed at a location other than the power supply portion 111 when the conductor arranged in a circle from the power supply portion 121 is divided into approximately two equal parts. 1 is loaded. The tertiary (mode 3) circular loop antenna 120 has five varactor diodes 120d, one at each of the six equal points on the circular conductor that is arranged from the power supply 121. 1 ~120d 5 is loaded. The fifth-order (mode 5) circular loop antenna 130 has nine varactor diodes 130d arranged at 10 positions, which are approximately 6 equal parts of a circular conductor arranged from a power supply 131. 1 ~130d 9 is loaded. The seventh order (mode 7) circular loop antenna 140 has a total of 13 varactor diodes 140d, one at each of 13 locations that divide the conductor arranged in a circle from the power supply 141 into 14 equal parts. 1 ~140d 14is loaded.

[0038] FIG. 4 shows an example of a cross-sectional configuration of the first loop antenna device 100. As shown in FIG. 4, the first loop antenna device 100 includes a first substrate 102 and a second substrate 103. The first substrate 102 is formed of, for example, a 0.1 mm substrate, and the second substrate 103 is formed of, for example, a 0.2 mm substrate, with a gap Da (air layer) of 1 mm between both substrates 103, 104. The first substrate 102 and the second substrate 103 are formed of, for example, an insulator called Megtron7 (product name). Conductors constituting the circular loop antennas 110, 120, 130, and 140 are arranged on the surface of the first substrate 102. Fig. 4 shows the location where the conductor of the circular loop antenna 110 is arranged, and the conductors of the circular loop antennas 120, 130, and 140 are not shown. Circular loop antenna 110 with varactor diode 110d 1 The conductor is cut at the point where the load is applied, and a varactor diode 110d is connected to connect the two cut conductors. 1 is connected.

[0039] First substrate 102 and second substrate 103 are connected by two connection pins 104, a conductor serving as reflector 105 is disposed on the front surface of second substrate 103, and a 50 Ω microstrip line 106 is disposed on the back surface of second substrate 103. The two connection pins 104 correspond to power supply section 111 shown in FIG. The microstrip line 106 is electrically connected to the connection pin 104 or the reflector 105 through a via hole 105a. The reflector 105 is different from the parabolic reflector member 101 shown in FIG.

[0040] A connector 107 is provided on the microstrip line 106. A ground potential portion 108 is arranged around the connector 107. A transmitting / receiving portion 151 (FIG. 2) is connected to the connector 107. During transmission, a transmission signal is supplied from the transmitting / receiving portion 151, and a varactor diode 110d 1During reception, a signal obtained at connector 107 is supplied to transmitting / receiving section 151.

[0041] 5 is a diagram showing the position of angle θ at which the current of the circular loop antenna is maximized, in which an example of a quintic circular loop antenna 130 is shown. First, the current I(Φ) when the circular loop antenna radiates an n-th order OAM wave is shown in the following formula 1. In the case of the circular loop antenna 130, n in formula 1 is 5.

[0042]

number

[0043] The maximum current point I of the 5th (nth) circular loop antenna 130 n 5A, can be expressed by nine positions each of which is an angular position θ from power supply unit 131. Angular position θ can be expressed by the following equation. θ=Kπ / n Here, K is a value that changes according to the arrangement position of the circular loop antenna 130, and n is the order (here, 5). The wireless communication frequency used here is 28 GHz band.

[0044] FIG. 5B shows nine maximum current points I n Varactor diode D 1 ~D 9 Here, the circular loop antenna 130 is equipped with a varactor diode D 1 ~D 9 When no voltage is applied to operate the varactor diode D 1 ~D 9 When the MOSFET is off, nine varactor diodes D 1 ~D 9 becomes the capacitor C. At this time, the circular loop antenna 130 can properly transmit and receive signals. On the other hand, a varactor diode D 1 ~D 9 When a voltage for operating the varactor diode D is applied from the voltage application unit 160, 1 ~D 9 As shown in Figure 5D, when the 9 varactor diodes D 1 ~D 9 becomes resistor R. This causes an electrical change in the loop length (increase in loss). This increase in loss can prevent interference with another circular loop antenna device placed adjacently.

[0045] Since the number of varactor diodes connected in series differs between the circular loop antennas 110, 120, 130, and 140, it is preferable to change the voltages applied by the voltage application unit 160 to the circular loop antennas 110, 120, 130, and 140 accordingly. For example, 1.35V is applied from the voltage application unit 160 to the circular loop antenna 110 in mode 1 with one varactor diode, 6.9V is applied from the voltage application unit 160 to the circular loop antenna 130 in mode 3 with five varactor diodes, 12.4V is applied from the voltage application unit 160 to the circular loop antenna 130 in mode 5 with nine varactor diodes, and 17.4V is applied from the voltage application unit 160 to the circular loop antenna 130 in mode 7 with 13 varactor diodes. The voltage values ​​applied vary depending on the characteristics of the varactor diodes used, etc.

[0046] 6 shows the results of measuring the short-distance transmission characteristics when the varactor diode is off and on for the circular loop antennas 110, 120, 130, and 140 of each mode. In each characteristic diagram shown in FIG. 6, the horizontal axis indicates frequency and the vertical axis indicates gain. The characteristics of mode 1 (upper left) in FIG. 6 show the characteristics of each antenna as viewed from circular loop antenna 110 in mode 1. The signal S51 is the characteristic of the circular loop antenna 110 itself in mode 1, and is the characteristic when the varactor diode is off. ONrepresents the characteristics when a voltage (1.35V) is applied to the circular loop antenna 110 and the varactor diode is turned on. When the varactor diode is turned on, the gain of the circular loop antenna 110 is reduced. This reduces the interference with the mode 1 circular loop antenna of another adjacent loop antenna device 300.

[0047] Note that signal S61 among the characteristics of circular loop antenna 110 in mode 1 is the short-distance passing characteristic of circular loop antenna 120 in mode 3, signal S71 is the short-distance passing characteristic of circular loop antenna 130 in mode 5, and signal S81 is the short-distance passing characteristic of circular loop antenna 120 in mode 3. These signals S61, S71, and S81 have lower gain than characteristic S51 of circular loop antenna 110 itself in mode 1, and circular loop antenna 110 can properly extract only the signal of mode 1.

[0048] 6 (upper right) shows the characteristics of each antenna as viewed from circular loop antenna 120 in mode 3. The signal S62 is the characteristic of the circular loop antenna 120 itself in mode 3, and is the characteristic when the varactor diode is off. ON represents the characteristics when a voltage (6.9V) is applied to the circular loop antenna 120 and the varactor diode is turned on. When the varactor diode is turned on, the gain of the circular loop antenna 120 decreases. This reduces the interference with the mode 3 circular loop antenna of another adjacent loop antenna device 300.

[0049] Note that signal S52 in the characteristics of circular loop antenna 120 in mode 3 is the short-distance passing characteristic of circular loop antenna 110 in mode 1, signal S72 is the short-distance passing characteristic of circular loop antenna 130 in mode 5, and signal S82 is the short-distance passing characteristic of circular loop antenna 140 in mode 3. These signals S52, S72, and S82 have lower gain than characteristic S62 of circular loop antenna 120 itself in mode 3, and circular loop antenna 120 can properly extract only the signal in mode 3.

[0050] The characteristics of mode 5 (lower left) in FIG. 6 show the characteristics of each antenna as viewed from circular loop antenna 130 in mode 5. The signal S73 is the characteristic of the circular loop antenna 130 itself in mode 5, and is the characteristic when the varactor diode is off. ON represents the characteristics when a voltage (12.4 V) is applied to the circular loop antenna 130 and the varactor diode is turned on. When the varactor diode is turned on, the gain of the circular loop antenna 130 decreases. This reduces the interference with the mode 5 circular loop antenna of another adjacent loop antenna device 300.

[0051] Note that signal S53 in the characteristics of circular loop antenna 130 in mode 5 is the short-distance passing characteristic of circular loop antenna 110 in mode 1, signal S63 is the short-distance passing characteristic of circular loop antenna 120 in mode 3, and signal S83 is the short-distance passing characteristic of circular loop antenna 140 in mode 7. These signals S53, S63, and S83 have lower gain than characteristic S73 of circular loop antenna 130 in mode 5 itself, and circular loop antenna 130 can properly extract only the signal in mode 5.

[0052] The characteristics of mode 7 (lower right) in FIG. 6 show the characteristics of each antenna as viewed from circular loop antenna 140 in mode 7. The signal S84 is the characteristic of the circular loop antenna 140 itself in mode 7, and is the characteristic when the varactor diode is off.ON represents the characteristics when a voltage (17.4 V) is applied to the circular loop antenna 140 and the varactor diode is turned on. When the varactor diode is turned on, the gain of the circular loop antenna 140 is reduced. This reduces the interference with the mode 7 circular loop antenna of another adjacent loop antenna device 300.

[0053] Incidentally, signal S54 among the characteristics of circular loop antenna 140 in mode 7 is the short-distance passing characteristic of circular loop antenna 110 in mode 1, signal S64 is the short-distance passing characteristic of circular loop antenna 120 in mode 3, and signal S74 is the short-distance passing characteristic of circular loop antenna 130 in mode 5. These signals S54, S64, and S74 have lower gain than characteristic S84 of circular loop antenna 140 in mode 7 itself, and circular loop antenna 140 can properly extract only the mode 7 signal.

[0054] As described above, according to the loop antenna transmission / reception system of this example, multiple (two) loop antenna devices 100, 300 can be arranged closely in one location as shown in FIG. 1, enabling one-to-many wireless transmission. In this case, varactor diodes are connected to the loop antenna devices 100, 300 arranged close to each other at the points where the current of each loop antenna is maximum, so that the two loop antenna devices 100, 300 can selectively transmit and receive signals, and the varactor diode of the loop antenna that is not communicating is turned on and the varactor diode of the loop antenna that is communicating is turned off. This makes it possible to reduce interference between the two (plurality of) loop antenna devices 100, 300 arranged closely to each other, and to appropriately perform multiplexed wireless communication of OAM waves.

[0055] In the above-described embodiment, the two loop antenna devices 100, 300 are arranged in one location to perform one-to-two multiplex communication, but two or more antenna devices may be arranged.

[0056] In the above-mentioned embodiment, the varactor diodes are loaded at all the points where the current is maximum. However, any one or more of the varactor diodes may be omitted. For example, as shown as the characteristics of mode 1 in FIG. 6, for the loop antenna 110 in mode 1, the difference in characteristics between the varactor diodes on and off is smaller than in other modes, and therefore the effect of suppressing interference is small, so the varactor diodes may be omitted. In addition, in the case of an antenna of another mode, some of the varactor diodes shown in Fig. 3 may be omitted. For example, the loading of every other one of the varactor diodes shown in Fig. 3 may be omitted.

[0057] Furthermore, in the configuration shown in FIG. 1 for performing point-to-multiple multiplex communication, interference suppression by loading varactor diodes may be omitted. [Explanation of symbols]

[0058] 100...first loop antenna device, 101...reflecting member, 102...first substrate, 103...second substrate, 104...connection pin, 105...reflecting plate, 105a...via hole 106...microstrip line, 107...connector, 108...ground potential portion 110,120,130,140...Circular loop antenna, 110d 1 ,120d 1 ~d 5 ,130d 1 ~d 9 ,140d 1 ~d 13 . . varactor diode; 111, 121, 131, 141... power supply section; 150, 151... transmitting / receiving section; 159... transmitting / receiving data processing section; 160... voltage application section; 200... second loop antenna device; 201... reflecting member 210, 220, 230, 240... circular loop antenna, 211... power supply unit, 250, 251... transmitting / receiving unit, 259... transmitting / receiving data processing unit, 300... third loop antenna device, 350... transmitting / receiving unit, 360... voltage application unit, 400... fourth loop antenna device, 401... reflecting member, 450... transmitting / receiving unit

Claims

1. a first loop antenna device in which a plurality of circular loop antennas, each having a perimeter length approximately equal to an integral multiple of a wavelength determined by a wireless communication frequency, are arranged concentrically on the same plane; A first reflecting member disposed on a rear side of the first loop antenna device; a second loop antenna device having the same configuration as the first loop antenna device, the second loop antenna device and the first loop antenna device being arranged with their front sides facing each other with their central axes aligned with each other; A second reflecting member disposed on a rear side of the second loop antenna device; a third loop antenna device arranged adjacent to the first loop antenna device on the same plane, the third loop antenna device including a plurality of circular loop antennas arranged concentrically on the same plane, the third loop antenna having a perimeter that is approximately an integral multiple of a wavelength determined by a wireless communication frequency; a third reflecting member disposed at a position spaced apart from the second reflecting member; a fourth loop antenna device having the same configuration as the third loop antenna device and the third reflecting member disposed on a rear side thereof, Wireless communication is performed between the first loop antenna device and the second loop antenna device, which are arranged facing each other with their central axes aligned, and wireless communication is also performed between the third loop antenna device and the fourth loop antenna device through a communication path that is reflected by the first reflecting member and the third reflecting member. Loop antenna transmitting and receiving system.

2. The first reflecting member, the second reflecting member, and the third reflecting member each have the same paraboloid shape.

2. The loop antenna transmitting and receiving system according to claim 1.

3. the first loop antenna device and the third loop antenna device selectively perform wireless communication with one another; the first loop antenna device and the third loop antenna device are each provided with a varactor diode whose characteristics change when turned on and off at least a part of an angular position at which a current density distribution determined by the wireless communication frequency is maximized, of a plurality of circular loop antennas; Among the first loop antenna device and the third loop antenna device, the varactor diode of the antenna device that performs wireless communication is turned off, and the varactor diode of the antenna device that does not perform wireless communication is turned on.

3. The loop antenna transmitting and receiving system according to claim 2.

4. A loop antenna device in which a plurality of circular loop antennas, each having a perimeter that is approximately an integral multiple of a wavelength determined by a wireless communication frequency, are arranged concentrically on the same plane, A varactor diode whose characteristics change when turned on and off is loaded at least in a part of the angular positions at which the current density distribution determined by the wireless communication frequency of the plurality of circular loop antennas is maximized. Loop antenna device.

5. When wireless communication is performed, the varactor diode is turned off, and when wireless communication is not performed, the varactor diode is turned on. The loop antenna device according to claim 4.

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