TW201720066A - Antenna apparatus, and method for transmitting and receiving signal - Google Patents

Abstract

An antenna apparatus (10) is provided with a plurality of antennas (11, 12) each including a matching circuit (11b, 12b), a control circuit (15) for controlling the matching circuit of each antenna and thereby adjusting the impedance of each antenna, and a wireless circuit (13) for processing the signals transmitted and received by each antenna. The control circuit selects one of the plurality of antennas, controls the matching circuit of the selected antenna to match the selected antenna and the wireless circuit, and controls the matching circuits of the unselected antennas so that the unselected antennas and the wireless circuit do not match. The control circuit controls the wireless circuit so as to output a signal to the selected antenna during signal transmission, and controls the wireless circuit so as to receive the signal from the selected antenna during signal reception.

Description

Antenna device and signal transmission and reception method

The present invention relates to an antenna device having a plurality of antennas and a signal transmitting and receiving method.

The antenna device disclosed in Patent Document 1 is known as an antenna device that transmits or receives a signal using a plurality of antennas. When the signal is transmitted or received, the antenna device matches any of the two antennas to the wireless circuit portion. Thereby, the antenna used for transmission or reception is switched. [Prior Technical Literature] [Patent Literature]

Japanese Special Open 2010-81161

[Problems to be Solved by the Invention] However, in the conventional configuration, coupling may occur between antennas. For example, when two antennas are placed at close range, such coupling occurs and the transmission level or reception level is reduced. The present invention has been made in view of such a problem, and an object thereof is to provide an antenna apparatus and a signal transmission and reception method capable of suppressing a decrease in transmission and reception levels at the time of signal transmission and reception. [The way to solve the problem]

An antenna device according to an aspect of the present invention includes: a plurality of antennas respectively including matching circuits for adjusting impedances; and a control circuit for adjusting impedances of the antennas by controlling the matching circuits of the antennas; and a wireless circuit Processing the signal transmitted and received by each of the antennas; and the control circuit selects one of the plurality of antennas, controls the matching circuit of the selected antenna, and achieves impedance matching between the selected antenna and the wireless circuit, and Controlling the matching circuit of the unselected antenna such that the unselected antenna does not match the impedance of the wireless circuit, and when the signal is transmitted, controlling the wireless circuit to output a signal to the selected antenna for signal reception The aforementioned wireless circuitry is controlled to receive signals from the selected antenna.

A signal transmission and reception method according to an aspect of the present invention transmits and receives a signal using a plurality of antennas, and includes: (a) selecting one of the plurality of antennas; and (b), selecting the foregoing The impedance of the antenna is adjusted to match the selected antenna to the wireless circuit; and in step (c), the impedance of the unselected antenna is adjusted such that the unselected antenna does not match the aforementioned wireless circuit. The aforementioned step (c) includes the step of disconnecting the unselected antenna from the wireless circuit or the step of disconnecting the wireless circuit to which the unselected antenna is connected. [Effects of the Invention]

The antenna device and the signal transmission and reception method suppress the decrease in the transmission/reception level at the time of signal transmission and reception.

BEST MODE FOR CARRYING OUT THE INVENTION Fig. 1(a) shows a system 1 used in an antenna apparatus according to the first embodiment. The system 1 is provided with: an electrical device 2 (for example, lighting); a switch 3 for operating the electrical device 2; and a controller 4 for controlling the electrical device 2. The illuminated switch 3 operates the illumination based on the signal transmitted from the controller 4. The controller 4 sometimes sends a signal to the switch 3 and sometimes receives the signal from the switch 3. The frequency of the signal is specified to be a specific frequency (for example, 426 MHz) in the range of 100 MHz to 10 GHz. In order to improve the reliability of transmission and reception between the switch 3 and the controller 4, a diversity effect is utilized. Specifically, the antenna device 10 (see FIG. 2) in the controller 4 includes a plurality of antennas.

Fig. 1(b) shows an example of a system 5 used in the antenna device shown in the second embodiment. The system 5 has: a plurality of electrical devices 6, 7; a first control device 6a (such as a switch) to operate the first electrical device 6; a second control device 7a, a second electrical device 7; and a management device 8, management A control device 6a and a second control device 7a. The first electrical device 6 is for example a lighting and the second electrical device 7 is for example a solar battery. The management device 8 communicates with the first control device 6a and the second control device 7 using signals having different frequencies. For example, the management device 8 communicates with the first control device 6a using a signal of a first frequency (eg, 426 MHz). The management device 8 communicates with the second control device 7a using a signal of a second frequency (e.g., 920 MHz). The antenna device 30 (see FIG. 6) of the management device 8 includes an antenna that transmits and receives a signal of a first frequency, and an antenna that transmits and receives a signal of a second frequency.

As described above, in the case where the electric device is controlled by a wireless signal, a plurality of antennas are disposed in the controller 4 or the management device 8. The configuration space of the controller 4 or the management device 8 is preferably small, and this size is limited. Therefore, the distance between the plurality of antennas disposed in the controller 4 or the management device 8 becomes close. Here, "near" means shorter than the following: the minimum distance between the antennas that do not couple between the complex antennas when transmitting or receiving signals. Therefore, in the case where the distance between the antennas is close, among these devices (the controller 4 or the management device 8), coupling may occur between the antennas at the time of signal transmission or reception. The antenna devices 10 and 30 (see FIGS. 2 and 6) shown below suppress coupling between the antennas.

(First Embodiment) An antenna device 10 according to a first embodiment will be described with reference to Figs. 2 and 3 . The antenna device 10 is used, for example, in the system 1 shown in Fig. 1(a). The antenna device 10 transmits and receives signals of a specific frequency (for example, 426 MHz) using a plurality of antennas 11, 12. The antenna device 10 includes a first antenna 11 , a second antenna 12 , a radio circuit 13 , a switching circuit 14 , a control circuit 15 , and a memory device 16 . The first antenna 11 has an antenna portion 11a and a matching circuit 11b. The antenna portion 11a is configured, for example, in a ring shape or a rod shape. The antenna portion 11a is connected to the ground. The second antenna 12 has an antenna portion 12a and a matching circuit 12b. The first antenna 11 and the second antenna 12 have the same configuration.

The matching circuit 11b is a circuit for changing the impedance of the first antenna 11. As shown in FIG. 3, in the case of a loop antenna, the matching circuit 11b can be disposed in the loop antenna. The matching circuit 11b includes a variable capacitance element 21 and a capacitance element 22. The variable capacitance element 21 represents an element that can perform electrostatic capacitance adjustment by an input signal (for example, application of a voltage). As the variable capacitance element 21, for example, a variable capacitance diode is used.

The wireless circuit 13 sometimes forms a transmission signal and sometimes processes the received signal received by the first antenna 11 or the second antenna 12. The switching circuit 14 is disposed between the first antenna 11 and the radio circuit 13 and between the second antenna 12 and the radio circuit 13. The switching circuit 14 switches to any one of the first connection state A1 and the second connection state A2 based on an instruction of the control circuit 15. The first connection state A1 indicates a state in which the switching circuit 14 connects the first antenna 11 to the wireless circuit 13 and does not connect the second antenna 12 to the wireless circuit 13. The second connection state A2 indicates a state in which the switching circuit 14 connects the second antenna 12 to the wireless circuit 13 and does not connect the first antenna 11 to the wireless circuit 13. In either of the first connection state A1 and the second connection state A2, the first antenna 11 and the second antenna 12 are in a non-connected state. The switching circuit 14 is constituted by, for example, a semiconductor switching element.

The control circuit 15 controls the first antenna 11, the second antenna 12, and the switching circuit 14 at the time of signal transmission and at the time of signal reception (including waiting for a wait signal). Specifically, the control circuit 15 causes the first antenna 11 and the second antenna 12 to be impedance-matched, and the impedance may not match the wireless circuit 13 in some cases.

Among the controls for impedance matching of the antennas 11, 12, the control circuit 15 adjusts the parameters (e.g., applied voltage) applied to the matching circuits 11b, 12b for causing the transmission level for the antennas 11, 12 of the radio circuit 13 or The receiving level becomes higher. The antennas 11 and 12 are previously set with parameters (applied voltage) whose impedance is matched to the wireless circuit 13. For example, when the antenna device 10 is manufactured, the applied voltages input to the matching circuits 11b and 12b are changed, and the impedance is detected to match the applied voltage of the wireless circuit 13 (the transmission level and the receiving level are higher than the first level). The applied voltage of the reference )). The detected applied voltage is recorded in the memory device 16 of the antenna device 10. Hereinafter, the parameter (applied voltage) at which the antenna impedance is matched to the wireless circuit 13 is referred to as a "matching signal".

In the control of impedance mismatch of the antennas 11, 12, the control circuit 15 adjusts the parameters (e.g., applied voltage) applied to the matching circuits 11b, 12b for transmitting the antennas 11, 12 for transmitting or receiving signals. The level or reception level becomes lower. The antennas 11 and 12 are set in advance with parameters (applied voltages) whose impedances do not match the radio circuit 13. For example, when the antenna device 10 is manufactured, the applied voltages input to the matching circuits 11b and 12b are changed, and the applied impedance is detected to be unmatched by the wireless circuit 13 (the transmission level and the receiving level are lower than the ratio). The first reference 値 the lower second reference 施加 applied voltage). The detected applied voltage is recorded in the memory device 16 of the antenna device 10. Hereinafter, the parameter (applied voltage) in which the antenna impedance does not match the radio circuit 13 is referred to as a "mismatch signal".

The operation of the antenna device 10 at the time of signal transmission will be described with reference to Figs. 2 and 4 . The control circuit 15 transmits the transmission signal using the first antenna 11 and the second antenna 12 at the time of signal transmission. Specifically, the control circuit 15 causes the switching circuit 14 to operate when the signal is transmitted, and connects the first antenna 11 and the second antenna 12 to the wireless circuit 13 in the first connection state A1 and the second connection state A2. Switch between periodically.

When the switching circuit 14 is in the first connection state A1, the control circuit 15 controls the respective antennas 11, 12 as follows. The control circuit 15 inputs the matching signal V11 to the matching circuit 11b of the first antenna 11 and impedance-matches the first antenna 11 to the wireless circuit 13, and inputs the mismatch signal V22 to the matching circuit 12b of the second antenna 12 and The impedance of the second antenna 12 is not matched to the wireless circuit 13. Further, while the matching signal V11 is input to the first antenna 11, the wireless circuit 13 outputs a transmission signal to the first antenna 11.

When the switching circuit 14 is in the second connection state A2, the control circuit 15 controls the respective antennas 11, 12 as follows. The control circuit 15 inputs the mismatch signal V12 to the matching circuit 11b of the first antenna 11 and the impedance of the first antenna 11 does not match the wireless circuit 13, and inputs the matching signal V21 to the matching circuit 12b of the second antenna 12. The second antenna 12 is impedance matched to the wireless circuit 13. Further, while the matching signal V21 is input to the second antenna 12, the wireless circuit 13 outputs the transmission signal to the second antenna 12. As described above, the antenna device 10 periodically switches the first antenna 11 and the second antenna 12 to transmit a transmission signal.

The operation of the antenna device 10 during standby of the signal reception and reception of the signal will be described with reference to Figs. 2 and 5 . The control circuit 15 alternately switches the first antenna 11 and the second antenna 12 to a receivable state during standby of signal reception. Specifically, the control circuit 15 causes the switching circuit 14 to operate when the signal is received, and the connection state between the first antenna 11 and the second antenna 12 and the wireless circuit 13 is in the first connection state A1 and The two connection states A2 are periodically switched.

When the switching circuit 14 is in the first connection state A1, the control circuit 15 controls the respective antennas 11, 12 as follows. The control circuit 15 inputs the matching signal V11 to the matching circuit 11b of the first antenna 11 and impedance-matches the first antenna 11 to the wireless circuit 13, and inputs the mismatch signal V22 to the matching circuit 12b of the second antenna 12 and The impedance of the second antenna 12 is not matched to the wireless circuit 13.

When the switching circuit 14 is in the second connection state A2, the control circuit 15 controls the respective antennas 11, 12 as follows. The control circuit 15 inputs the mismatch signal V12 to the matching circuit 11b of the first antenna 11 and the impedance of the first antenna 11 does not match the wireless circuit 13, and inputs the matching signal V21 to the matching circuit 12b of the second antenna 12. The second antenna 12 is impedance matched to the wireless circuit 13.

Further, the control circuit 15 compares the output signals of the two antennas 11, 12 with the threshold 値. When the control circuit 15 determines which of the output signals is higher than the threshold ,, the TC compares the output signal of the first antenna 11 with the output signal of the second antenna 12 during the predetermined comparison period, and selects the antenna whose output level is high. Moreover, the selected antenna is connected to the wireless circuit 13 by the switching circuit 14. Furthermore, the control circuit 15 controls the matching circuits 11b, 12b to impedance match the selected antenna to the wireless circuit 13 and to make the unselected antenna and the wireless circuit 13 impedance mismatch.

Next, the action of the control circuit 15 will be explained. In the prior art, one of the first antenna 11 and the second antenna 12 is impedance matched, and the other is impedance mismatch. Even in such a configuration, the coupling between the two antennas 11 and 12 is also lowered, but there is a case where sufficient gain cannot be achieved based on the coupling of the two antennas 11 and 12. The reason for this is that although the two antennas 11 and 12 have a difference in gain, the two antennas 11 and 12 operate together at the time of transmission and reception, and the two antennas 11 and 12 are coupled. Thus, as described above, the control circuit 15 connects an antenna to the radio circuit 13 and inputs the matching signal to an antenna when the transmission signal is transmitted, when the signal is received, or when the reception signal is received, so that an antenna impedance is matched. In the wireless circuit 13. Furthermore, the antenna impedance is not matched to the wireless circuit 13 by the other antenna not being connected to the wireless circuit 13 and inputting the mismatch signal to the other antenna. As a result, the two antennas 11 and 12 generate a difference in gain, and an electric field is less likely to be formed in the unselected antenna, so that the coupling between the two antennas 11 and 12 is lowered. Moreover, since the two antennas 11 and 12 are not connected, the coupling via the circuit (that is, the conductor formed on the substrate or the capacitor member on the substrate) is also suppressed.

(Second Embodiment) An antenna device 30 according to a second embodiment will be described with reference to Fig. 6 . The antenna device 30 of the second embodiment is used, for example, in the system 5 shown in Fig. 1(b). The antenna device 30 transmits and receives signals having different frequencies using a plurality of antennas.

The antenna device 30 includes a first antenna 31, a second antenna 32, a first wireless circuit 33 connected to the first antenna 31, a second wireless circuit 34 connected to the second antenna 32, a control circuit 35, and a memory device. 36. The first antenna 31 has an antenna portion 31a and a matching circuit 31b. The second antenna 32 has an antenna portion 32a and a matching circuit 32b. The configurations of the antenna portions 31a and 32a and the matching circuits 31b and 32b are as shown in the first embodiment. The memory device 36 is based on the first embodiment and stores the matching signal and the mismatch signal (that is, the respective applied voltages) set by the respective antennas 31 and 32.

The first wireless circuit 33 sometimes forms a transmission signal of a specific frequency (for example, 426 MHz) and sometimes a reception signal of a specific frequency received by the first antenna 31. The second wireless circuit 34 either forms a transmission signal of a specific frequency (e.g., 920 MHz) or processes a reception signal of a specific frequency received by the second antenna 32. The signal processed by the first wireless circuit 33 is different from the frequency of the signal processed by the second wireless circuit 34.

The control circuit 35 controls the first antenna 31 and the second antenna 32 at the time of signal transmission and signal reception. Specifically, the control circuit 35 causes the first antenna 31 and the second antenna 32 to be impedance-matched to the wireless circuit, and the impedance may not match the wireless circuit. The control of the first embodiment is controlled by matching the antenna impedance to the control of the radio circuit and the control of the antenna impedance not matching the radio circuit.

The operation of the antenna device 30 will be described. When the signal is transmitted, the control circuit 35 selects either of the first antenna 31 and the second antenna 32, and transmits the transmission signal with the selected antenna. Moreover, control circuit 35 controls the matching circuit of the selected antenna for matching the selected antenna to the transmission frequency of the radio circuit connected to the selected antenna. Further, the control circuit 35 controls the matching circuit of the selected antenna and controls the matching circuit of the unselected antenna for making the unselected antenna and the wireless circuit connected to the unselected antenna not match at the transmission frequency. The control methods of the matching circuits 31b and 32b are according to the first embodiment. Moreover, the control circuit 35 operates only the wireless circuits of the first wireless circuit 33 and the second wireless circuit 34 that are connected to the selected antenna, so that the wireless circuit connected to the unselected antenna does not operate.

The control circuit 35 alternately switches the first antenna 31 and the second antenna 32 to a receivable state during standby of signal reception. The control circuit 35 controls the matching circuits 31b, 32b such that the selected antenna is matched to the radio circuit connected to the selected antenna at the receiving frequency, and the unselected antenna is connected to the radio circuit connected to the unselected antenna. The receiving frequency is not matched. The control methods of the matching circuits 31b and 32b are according to the first embodiment. Moreover, the control circuit 35 operates only the wireless circuits of the first wireless circuit 33 and the second wireless circuit 34 that are connected to the selected antenna, so that the wireless circuit connected to the unselected antenna does not operate.

Further, when receiving signals are received by any of the antennas, the control circuit 35 controls the matching circuits of the respective antennas 31, 32 as follows. That is, the control circuit 35 controls a matching circuit that receives the received signal to one of the antennas for matching the antenna to the receiving circuit to the radio circuit connected to the antenna. Also, the control circuit 35 controls the matching circuit of the other antenna for causing the other antenna to be mismatched at the receiving frequency with the wireless circuit connected to the other antenna. At this time, the control circuit 35 operates the wireless circuit connected to the impedance-matched antenna, leaving the other wireless circuits inoperative.

Next, the action of the control circuit 35 will be explained. In the present embodiment, the frequencies at which the signals transmitted and received by the respective antennas 31 and 32 are different are different. When the frequency of one signal becomes an integer multiple of the frequency of another signal or is close to it (for example, 426 MHz and 920 MHz), when signals are transmitted and received, coupling between the antennas 31 and 32 occurs, and sufficient gain cannot be obtained. situation. Thus, as described above, when the transmission signal is transmitted, when the signal is received, or when the reception signal is received, the control circuit 35 causes the antenna and the wireless circuit connected to the antenna to transmit by controlling the matching circuit of the selected antenna. The receiving frequency is a match. On the other hand, by controlling the matching circuit of the unselected antenna, the antenna and the wireless circuit connected to the antenna do not match the transmission and reception frequencies. Furthermore, control circuit 35 disables the wireless circuitry connected to the unselected antenna. Thereby, the two antennas 31 and 32 generate a difference in gain, and an electric field is less likely to be formed in the unselected antenna, so that the coupling between the two antennas 31 and 32 is lowered.

The effects of the antenna devices 10 and 30 of the above embodiments will be described. (A) Among the antenna devices 10 (30) of the first and second embodiments, the control circuit 15 (35) performs the following control.

When the signal is transmitted, the control circuit 15 (35) controls the wireless circuit 13 (33, 34) to match the selected antenna with the wireless circuit connected to the selected antenna at the transmission frequency, and output only the transmission signal to The antenna chosen.

Moreover, when the signal is received, the radio circuit 13 (33, 34) is controlled to match the selected antenna with the radio circuit connected to the selected antenna at the reception frequency and receive the signal only from the selected antenna. . Thereby, an electric field is less likely to be generated in the unselected antenna, and coupling between the two antennas 11 and 12 (31, 32) is suppressed, and the decrease in the transmission/reception level is suppressed at the time of signal transmission and reception.

(2) The antenna device 10 of the first embodiment transmits and receives a signal of a specific frequency and has a switching circuit 14. At the time of transmission and reception of the signal, the control circuit 15 controls the switching circuit 14, and connects the selected antenna and the radio circuit 13, and does not connect the unselected antenna and the radio circuit 13. With this configuration, the two antennas are not connected, so coupling between the two antennas 11 and 12 via the wireless circuit 13 is less likely to occur.

(3) The antenna device 30 of the second embodiment transmits and receives a plurality of signals of a specific frequency. Control circuit 35 matches the selected antenna to the radio circuitry connected to the selected antenna at the transmit and receive frequencies and operates the radio circuit connected to the selected antenna. Again, control circuit 35 mismatches the unselected antenna with the wireless circuitry connected to the unselected antenna and disables the wireless circuitry connected to the unselected antenna. Thereby, since the suppression electric field is formed on the unselected antenna, the coupling between the two antennas 31, 32 is suppressed.

(4) According to the signal transmission and reception method according to the first embodiment and the second embodiment, the electric field is less likely to be generated in the unselected antenna, and the coupling between the two antennas 11 and 12 (31, 32) is suppressed. When the signal is transmitted and received, the decrease of the transmission and reception levels is suppressed.

[Other Embodiments] In the first and second embodiments, the antenna devices 10 and 30 include two antennas, but the number of antennas may be three or more. In this case, the antennas used are switched in sequence. Further, the configuration of the matching circuits 11b, 12b, 31b, and 32b is not limited to the embodiment, and may include a coil or a resistor.

The technical idea that can be grasped by the above embodiments is described below. (Appendix 1) An antenna device (10; 30) having: a plurality of antennas (11, 12; 31, 32) respectively including matching circuits (11b, 12b; 31b, 32b) for adjusting impedance; 15; 35) adjusting the impedance of each of the antennas by controlling the matching circuit of each of the antennas; and the wireless circuit (13; 33; 34) processing the signal transmitted and received by each of the antennas; and the control circuit, Selecting any one of the plurality of antennas, controlling the matching circuit of the selected antenna to achieve impedance matching between the selected antenna and the wireless circuit, and controlling the matching circuit of the unselected antenna to make the foregoing unselected The antenna does not match the impedance of the wireless circuit, and when the signal is transmitted, the wireless circuit is controlled to output a signal to the selected antenna, and when the signal is received, the wireless circuit is controlled to be a signal from the selected antenna. Receive it.

(Appendix 2) The antenna device (10) according to Appendix 1, further comprising: a switching circuit (14) that connects the wireless circuit (13) to any one of the plurality of antennas (11, 12); The control circuit (15) controls the switching circuit to connect the selected antenna and the wireless circuit without connecting the unselected antenna and the wireless circuit during transmission and reception of a signal.

(Appendix 3) The antenna device (30) according to Appendix 1, wherein the radio circuit (33; 34) is one of a plurality of radio circuits (33, 34) that process signals having different frequencies, the plural Each of the antennas (31, 32) is connected to one of the plurality of wireless circuits (33, 34), and the plurality of antennas transmit and receive signals having different frequencies, the control circuit (35), the signal When transmitting and receiving, the wireless circuit connected to the selected antenna is operated, and the wireless circuit connected to the unselected antenna is not operated.

(Appendix 4) A signal transmitting and receiving method for transmitting and receiving a signal using a plurality of antennas (11, 12; 31, 32), comprising: step (a), selecting any one of the plurality of antennas; Adjusting the impedance of the selected antenna to match the selected antenna to the wireless circuit (13; 33; 34); and in step (c), adjusting the impedance of the unselected antenna to an unacceptable The selected antenna does not match the aforementioned wireless circuit; and the foregoing step (c) includes the steps of: disconnecting the unselected antenna from the wireless circuit, or connecting the wireless circuit connected to the unselected antenna The steps of operation.

1‧‧‧ system
2‧‧‧Electrical equipment
3‧‧‧ switch
4‧‧‧ Controller
5‧‧‧ system
6‧‧‧Electrical equipment
6a‧‧‧First control unit
7‧‧‧Electrical equipment
7a‧‧‧Second control device
8‧‧‧Management device
10‧‧‧Antenna device
11‧‧‧First antenna
11a‧‧‧Antenna Department
11b‧‧‧Matching line
12‧‧‧second antenna
12a‧‧‧Antenna Department
12b‧‧‧matching circuit
13‧‧‧Wireless circuits
14‧‧‧Switching circuit
15‧‧‧Control circuit
16‧‧‧ memory device
21‧‧‧Variable Capacitance Components
22‧‧‧Capacitive components
30‧‧‧Antenna device
31‧‧‧First antenna
31a‧‧‧Antenna Department
31b‧‧‧Matching circuit
32‧‧‧second antenna
32a‧‧‧Antenna crossing
32b‧‧‧matching circuit
33‧‧‧First wireless circuit
34‧‧‧Second wireless circuit
35‧‧‧Control circuit
36‧‧‧ memory device
A1‧‧‧First connection status
A2‧‧‧Second connection status
V11, V21‧‧‧ matching signal
V12, V22‧‧‧ mismatch signal
TC‧‧‧ scheduled comparison period

Fig. 1(a) is a schematic view showing a system used in the antenna device of the first embodiment, and Fig. 1(b) is a schematic view showing a system used in the antenna device of the second embodiment. Fig. 2 is a block diagram showing an antenna apparatus of the first embodiment. 3 is a circuit diagram of a first antenna of the antenna device of FIG. 2. Fig. 4 is a timing chart of the antenna device at the time of signal transmission. Fig. 5 is a timing chart of the antenna device at the time of signal reception. Figure 6 is a block diagram of an antenna device of a second embodiment.

1‧‧‧ system

2‧‧‧Electrical equipment

3‧‧‧ switch

5‧‧‧ system

6‧‧‧Electrical equipment

6a‧‧‧First control unit

7‧‧‧Electrical equipment

7a‧‧‧Second control device

8‧‧‧Management device

Claims (4)

An antenna device comprising: a plurality of antennas respectively including matching circuits for adjusting impedances; a control circuit for adjusting impedances of the antennas by controlling the matching circuits of the antennas; and a wireless circuit for processing each of the antennas Transmitting the received signal; and the control circuit selects any one of the plurality of antennas, controls the matching circuit of the selected antenna to achieve impedance matching between the selected antenna and the wireless circuit, and the control is not selected The matching circuit of the antenna causes the unselected antenna to not match the impedance of the wireless circuit, and when the signal is transmitted, the wireless circuit is controlled to output a signal to the selected antenna, and when the signal is received, the wireless The circuit is controlled to receive signals from the selected antenna. The antenna device according to claim 1, further comprising: a switching circuit that connects the wireless circuit to any one of the plurality of antennas; and the control circuit switches the signal during transmission and reception of the signal The circuit is controlled to connect the selected antenna to the wireless circuit and not to connect the unselected antenna to the wireless circuit. The antenna device according to claim 1, wherein the wireless circuit is one of a plurality of wireless circuits that process signals having different frequencies, and each of the plurality of antennas is connected to the plurality of wireless circuits. And the plurality of antennas transmit and receive signals having different frequencies; the control circuit operates the wireless circuit connected to the selected antenna during transmission and reception of the signal, and connects to the unconnected The wireless circuit of the selected antenna does not operate. A signal transmitting and receiving method for transmitting and receiving a signal by using a plurality of antennas, comprising: (a) selecting one of the plurality of antennas; and (b) adjusting the impedance of the selected antenna to the The selected antenna is matched to the wireless circuit system; and in step (c), the impedance of the unselected antenna is adjusted such that the unselected antenna does not match the wireless circuit system; and the step (c) includes The step of disconnecting the unselected antenna from the wireless circuit or the step of disconnecting the wireless circuit connected to the unselected antenna.