JP2014064130A - Antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna device capable of appropriately switching the antenna even when a matching circuit which causes a capacitive coupling is used.SOLUTION: An antenna device 1 includes: an inverted L-type antenna 2; a helical antenna 3; a radio circuit 4; high frequency switches 5, 11 and 12; and matching circuits 6 and 7. When the high frequency switch 5 connects the radio circuit 4 to the inverted L-type antenna 2, the high frequency switch 12 is opened, and a channel between the radio circuit 4 and the helical antenna 3 is shut off. When the high frequency switch 5 connects the radio circuit 4 to the helical antenna 3, the high frequency switch 11 is opened, and a channel between the radio circuit 4 and the inverted L-type antenna 2 is shut off. With this, a power supply channel to an antenna which is not connected by the high frequency switch 5 is shut off.

Description

  The present invention relates to an antenna device that transmits or receives radio waves by a polarization diversity method.

  2. Description of the Related Art Diversity antenna devices that switch and connect two antennas to transmit or receive radio waves have been known. For example, Patent Document 1 discloses a switch connected to a high-frequency circuit having a transmission circuit and a reception circuit, a phase adjustment circuit to which two antennas are connected, and an impedance disposed between the switch and the phase adjustment circuit. An antenna device including an adjustment unit is disclosed.

  FIG. 5 shows a configuration of an antenna device using a polarization diversity system different from that of Patent Document 1 as a reference example. The antenna device 100 includes an inverted L antenna 2, a helical antenna 3, a radio circuit 4, a high frequency switch 5, matching circuits 6 and 7, and a control circuit 8. The inverted L-shaped antenna 2 transmits or receives horizontally polarized waves. The helical antenna 3 transmits or receives vertically polarized waves. The radio circuit 4 outputs an AC signal and transmits radio waves. The AC signal to be transmitted is a signal that is modulated and superimposed on a carrier wave. The radio circuit 4 demodulates the radio wave received by tuning and restores the original signal. The high frequency switch 5 alternatively connects either the inverted L-type antenna 2 or the helical antenna 3 and the feeding point 4 a of the radio circuit 4. The matching circuits 6 and 7 are inserted between the high-frequency switch 5 and the antennas 2 and 3 to perform impedance matching between the antennas 2 and 3 and the radio circuit 4, thereby increasing the transmission efficiency of the AC signal. The matching circuits 6 and 7 each have a capacitor and are connected to the feeding point 4a of the wireless circuit 4 through the ground. The control circuit 8 controls operations of the radio circuit 4 and the high frequency switch 5.

  5A shows a state in which power is supplied from the wireless circuit 4 to the inverted L-type antenna 2, and FIG. 5B shows a state in which power is supplied from the wireless circuit 4 to the helical antenna 3. The connection between the radio circuit 4 and one of the antennas is switched by a high frequency switch 5 that operates based on a control signal output from the control circuit 8.

Japanese Patent Laid-Open No. 2005-236884

  In FIG. 5A, the high frequency switch 5 connects the feeding point 4a of the wireless circuit 4 and the matching circuit 6, and as indicated by the solid line arrow, the wireless circuit 4, the high frequency switch 5, the matching circuit 6, and the inverted L type. Power is supplied to a path constituted by the antenna 2. In this state, the connection between the feeding point 4 a of the wireless circuit 4 and the matching circuit 7 is interrupted by the high frequency switch 5.

  However, the feeding point 4a of the wireless circuit 4 and the matching circuit 7 are connected via a ground, and the matching circuit 7 is provided with a capacitor having a capacitance component. Therefore, as indicated by a broken line arrow, the ground and the matching circuit 7 are electrically connected by capacitive coupling, and power is also supplied to the path constituted by the radio circuit 4, the ground, the matching circuit 7, and the helical antenna 3. As a result, not only the inverted L-type antenna 2 but also the helical antenna 3 that should have been disconnected from the feeding point 4a by the high-frequency switch 5 is fed, and the antenna cannot be switched appropriately.

  In FIG. 5B, the high frequency switch 5 connects the feeding point 4a of the wireless circuit 4 and the matching circuit 7, and as indicated by the solid line arrows, the wireless circuit 4, the high frequency switch 5, the matching circuit 7, and the helical antenna 3 are connected. The same applies to the case where power is supplied to the path constituted by the above. That is, since the feeding point 4a of the wireless circuit 4 and the matching circuit 6 are connected via a ground, the wireless circuit 4, the ground, the matching circuit 6 and the inverted L-type are connected by capacitive coupling as indicated by a broken line arrow. Power is also supplied to the path constituted by the antenna 2. As a result, not only the helical antenna 3 but also the inverted L-type antenna 2 that should have been disconnected from the feeding point 4a by the high-frequency switch 5 is fed, and the antenna cannot be switched appropriately.

  The same applies to the case where the matching circuit 6 and the matching circuit 7 are inductively coupled by an inductive component such as a coil and are electrically connected to the ground. In such an antenna device 100, when the matching circuits 6 and 7 are eliminated, the antenna can be switched appropriately by the high-frequency switch 5, but the impedance is mismatched and the signal transmission efficiency is lowered.

  The present invention has been made in order to solve the above-described problem, and an antenna that has a capacitive component or an inductive component and can be switched satisfactorily even using a matching circuit that causes capacitive coupling or inductive coupling. An object is to provide an apparatus.

  In order to achieve the above object, an antenna device according to the present invention includes a first antenna that receives a radio wave transmitted with a first polarization or transmits a radio wave with the first polarization, and the first polarization. Receiving a radio wave transmitted by a second polarized wave different from the first antenna, or receiving a radio wave received by the first antenna or the second antenna. Or a radio circuit that transmits a radio wave transmitted by the first antenna or the second antenna, an antenna switching unit that selectively switches connection between the radio circuit and the first antenna or the second antenna, and An antenna apparatus comprising: a first matching circuit that matches an impedance between a first antenna and the radio circuit; and a second matching circuit that matches an impedance between the second antenna and the radio circuit. A first antenna switching path provided on a path from the radio circuit to the first antenna, and opened and closed in conjunction with a switching operation of the antenna switching unit; and provided on a path from the radio circuit to the second antenna. A second antenna switching path that opens and closes in conjunction with the switching operation of the antenna switching unit, and when the antenna switching unit connects the radio circuit and the first antenna, the second antenna switching When the path is opened, the path between the radio circuit and the second antenna is blocked, and when the antenna switching unit connects the radio circuit and the second antenna, the first antenna switching path is opened. Then, a path between the radio circuit and the first antenna is blocked.

  In the present invention, the first antenna switching path is provided in a path from the first matching circuit to the first antenna, and the second antenna switching path is a path from the second matching circuit to the second antenna. Is preferably provided.

  In this invention, the first antenna switching path is provided in a path from the radio circuit to the first matching circuit, and the second antenna switching path is provided in a path from the radio circuit to the second matching circuit. It is preferable that

  In the present invention, the radio circuit, the first matching circuit, and the second matching circuit are connected via a ground, and the first antenna switching path is provided in a path from the ground to the first matching circuit. Preferably, the second antenna switching path is provided in a path from the ground to the second matching circuit.

  In this invention, it is preferable that the first matching circuit and the second matching circuit are configured by a single path switching unit.

  In this invention, it further includes a radio wave intensity detection unit that detects the radio wave intensity received by the radio circuit, and the radio wave intensity detection unit performs the reception or transmission of the radio wave based on the radio wave intensity detected for each antenna. It is preferable to select an antenna to which the antenna switching unit is connected.

  In this invention, it further includes a time counting unit that counts time, and based on the radio wave intensity detected by the radio wave intensity detection unit after a predetermined time has elapsed since the antenna switching unit switched the antenna connection, It is preferable to select an antenna to which the antenna switching unit is connected for transmission.

  According to the antenna device of the present invention, when the antenna switching unit connects the radio circuit and the first antenna, the second antenna switching path opens a path between the radio circuit and the second antenna. The antenna is electrically disconnected from the radio circuit. Thereby, even if it uses the 2nd matching circuit which a capacitive coupling or an inductive coupling produces, the electric power feeding path from a radio | wireless circuit to a 2nd antenna can be interrupted | blocked. Similarly, when the antenna switching unit connects the radio circuit and the second antenna, the first antenna switching path opens a path between the radio circuit and the first antenna, so that the first antenna is electrically connected from the radio circuit. Separated. Thereby, even if it uses the 1st matching circuit which a capacitive coupling or an inductive coupling uses, the electric power feeding path from a radio | wireless circuit to a 1st antenna can be interrupted | blocked. In other words, the antenna switching unit and the first antenna switching path and the second antenna switching path are interlocked to electrically disconnect the antenna that is not connected by the antenna switching unit from the radio circuit, so that the antenna can be switched satisfactorily. it can.

The perspective view showing the schematic structure of the antenna device by one embodiment of the present invention. A circuit diagram showing composition of the antenna device. The circuit diagram which shows the structure of the modification of the antenna apparatus. The circuit diagram which shows the structure of another modification of the antenna apparatus. The circuit diagram which shows the structure of the conventional antenna apparatus.

  An antenna device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an antenna device. The antenna device 1 includes a circuit board 10, an inverted L-type antenna (first antenna) 2 provided so as to protrude from the circuit board 10, a helical antenna (second antenna) 3, and the like. The inverted L antenna 2 transmits or receives horizontal polarization (first polarization) parallel to the XY plane in the drawing. The helical antenna 3 transmits or receives vertical polarization (second polarization) parallel to the Z-axis direction (perpendicular to the XY plane) in the drawing. The circuit board 10 has a solid pattern constituting a ground and a component mounting surface. The solid ground pattern is formed on the front surface layer, the back surface layer, or the intermediate layer of the circuit board 10. The component mounting surface is formed on the front surface layer or the back surface layer of the circuit board 10.

  FIG. 2 shows a circuit configuration of the antenna device 1. The antenna device 1 includes a radio circuit 4, a high frequency switch (antenna switching unit) 5, a matching circuit (first matching circuit) 6, and a matching circuit (second matching circuit) 7. The antenna device 1 includes a control circuit (a radio wave intensity detection unit, a time counting unit) 8, a high frequency switch (first antenna switch) 11, and a high frequency switch (second antenna switch) 12. Components constituting the wireless circuit 4, the high-frequency switch 5, the matching circuits 6 and 7, the control circuit 8, the high-frequency switches 11 and 12 are mounted on the component mounting surface of the circuit board 10.

  The radio circuit 4 outputs an AC signal from the feeding point 4a and transmits radio waves. The AC signal to be transmitted is a signal that is modulated and superimposed on a carrier wave. The radio circuit 4 demodulates the radio wave received by tuning and restores the original signal. The high-frequency switch 5 is composed of a three-terminal switch with one input and two outputs (SPDT: Single Pole Dual Throw), and either the feeding point 4a of the radio circuit 4 and the inverted L-type antenna 2 or the helical antenna 3 is used. And alternatively. That is, when the high frequency switch 5 connects the radio circuit 4 and the matching circuit 6, the radio circuit 4 and the inverted L-type antenna 2 are connected via the matching circuit 6. Further, the radio frequency switch 5 connects the radio circuit 4 and the matching circuit 7, whereby the radio circuit 4 and the helical antenna 3 are connected via the matching circuit 7.

  The matching circuits 6 and 7 are inserted between the high-frequency switch 5 and the antennas 2 and 3, respectively, and perform impedance matching between the antennas 2 and 3 and the radio circuit 4 to increase the transmission efficiency of AC signals. . Each of the matching circuits 6 and 7 has a capacitor serving as a capacitance component, and is connected to the feeding point 4a of the wireless circuit 4 through the ground. The matching circuit 6 and the matching circuit 7 are arranged at a distance equal to or less than a quarter wavelength (λ / 4: λ is a wavelength) of a frequency used for transmission and reception of radio waves.

  The control circuit 8 controls operations of the radio circuit 4, the high frequency switch 5, the high frequency switches 11 and 12, and the like. For example, the control circuit 8 outputs a control signal that triggers an opening / closing operation to the high-frequency switch 5, the high-frequency switches 11, 12, and the like. At this time, the control circuit 8 outputs a control signal so that the connection operation of the high-frequency switch 5 and the connection operation of the high-frequency switches 11 and 12 are interlocked. Further, the control circuit 8 is provided with a radio wave intensity detecting function for detecting the radio wave intensity received by the radio circuit 4 and a time counting function for counting time.

  The high-frequency switches 11 and 12 are each composed of a two-terminal switch with one input and one output (SPST: Single Pole Single Throw). In the present embodiment, a PIN diode (p-intrinsic-n Diode), a FET (Field effect transistor), or the like is applied as the high-frequency switch. Features of the high-frequency switch include a high switching speed of 10 to 300 ns, a small insertion loss during closing, a sufficiently large isolation during opening, and capacitive coupling and inductive coupling are unlikely to occur. It is done. Therefore, by providing the high frequency switches 11 and 12 in the path from the radio circuit 4 to the inverted L-shaped antenna 2 and the helical antenna 3, the antenna that is not connected to the radio circuit 4 by the high frequency switch 5 is electrically connected from the radio circuit 4. Can be separated.

  The high-frequency switch 11 is provided in a path from the wireless circuit 4 to the inverted L-type antenna 2 through the ground, in particular, a path from the matching circuit 6 to the inverted L-type antenna 2, and interlocks with the switching operation of the high-frequency switch 5. Open and close. The high frequency switch 12 is provided in a path from the matching circuit 7 to the helical antenna 3 among the paths from the radio circuit 4 to the helical antenna 3 through the ground, and opens and closes in conjunction with the switching operation of the high frequency switch 5.

  As shown in FIG. 2A, when the high-frequency switch 5 connects the radio circuit 4 and the inverted L-type antenna 2, the radio-frequency switch 11 is closed (turned on), whereby the radio circuit 4 and the inverted L-type antenna are connected. 2 (path between the matching circuit 6 and the inverted L-type antenna 2) is electrically connected. Further, when the high frequency switch 12 is opened (off), the path between the radio circuit 4 and the helical antenna 3 (path between the matching circuit 7 and the helical antenna 3) is electrically cut off. As a result, the power supply path from the wireless circuit 4 to the helical antenna 3 through the ground as shown by the broken-line arrow in FIG.

  On the other hand, as shown in FIG. 2B, when the high frequency switch 5 connects the radio circuit 4 and the helical antenna 3, the high frequency switch 11 is opened so that the radio circuit 4 and the inverted L antenna 2 are connected. (Path between the matching circuit 6 and the inverted L-type antenna 2) is electrically cut off. As a result, the power supply path from the wireless circuit 4 to the inverted L-type antenna 2 through the ground as shown by the broken-line arrow in FIG. 5B is blocked. Further, when the high frequency switch 12 is closed, the path between the radio circuit 4 and the helical antenna 3 (the path between the matching circuit 7 and the helical antenna 3) is electrically connected. That is, since the high frequency switches 11 and 12 operate in conjunction with the high frequency switch 5, the high frequency switch 12 is opened when the high frequency switch 11 is closed, and the high frequency switch 12 is opened when the high frequency switch 11 is opened. Is closed.

  As already described, the high-frequency switches 5, 11, and 12 operate according to the control signal output from the control circuit 8. The control circuit 8 has a function of detecting the received signal strength indication (RSSI) received by the radio circuit 4 for each antenna. The control circuit 8 detects the intensity of the radio wave received by the radio circuit 4 for each antenna while periodically switching the antenna by operating the high frequency switches 5, 11 and 12. Then, the control circuit 8 selects an antenna to be used for receiving or transmitting a radio wave based on the radio wave intensity detected for each antenna, and outputs a control signal to be used for receiving or transmitting the radio wave. Switch the antenna.

  The control circuit 8 has a timer function for counting time. Immediately after the antenna connection is switched by the high-frequency switches 5, 11, and 12, the strength of the radio wave received by the wireless circuit 4 becomes unstable, and the strength of the radio wave becomes stable after a lapse of a minute time. Therefore, when the control circuit 8 detects the intensity of the radio wave received by the radio circuit 4 while switching the antenna, the control circuit 8 detects the intensity of the received radio wave after a predetermined time has elapsed since the high frequency switch 5 switched the connection of the antenna. Here, the predetermined time counted by the control circuit 8 is set to a time until the intensity of the radio wave received by the wireless circuit 4 is sufficiently stabilized after switching the antenna connection. Thereby, the intensity | strength of an exact received radio wave can be detected for every antenna, and the antenna used for reception or transmission of an electromagnetic wave can be selected appropriately.

  According to the antenna device 1 having the above configuration, when the high-frequency switch 5 connects the radio circuit 4 and the inverted L-type antenna 2, the high-frequency switch 12 is connected between the radio circuit 4 and the helical antenna 3 (matching). A path between the circuit 7 and the helical antenna 3 is opened. As a result, the helical antenna 3 is electrically disconnected from the radio circuit 4, and the power supply path from the radio circuit 4 to the helical antenna 3 can be cut off even using the matching circuit 7 in which capacitive coupling or inductive coupling occurs. Similarly, when the high frequency switch 5 connects the radio circuit 4 and the helical antenna 3, the high frequency switch 11 is connected between the radio circuit 4 and the inverted L antenna 2 (between the matching circuit 6 and the inverted L antenna 2). ), The inverted L-shaped antenna 2 is electrically disconnected from the radio circuit 4. Thereby, even if it uses the matching circuit 6 in which capacitive coupling or inductive coupling is used, the electric power feeding path from the radio | wireless circuit 4 to the reverse L-type antenna 2 can be interrupted | blocked. That is, by interlocking the high-frequency switch 5 with the high-frequency switch 11 and the high-frequency switch 12, the power supply path to the antenna that is not connected by the high-frequency switch 5 can be cut off, and the antenna can be switched satisfactorily. Further, since the above-described operation and effects are obtained by the high frequency switches 11 and 12 provided between the matching circuit 6 and the inverted L-type antenna 2 and between the matching circuit 7 and the helical antenna 3, the ground and the matching circuit are provided. 6 and the matching circuit 7 can be simplified.

  Further, the control circuit 8 selects an antenna to be used for receiving or transmitting a radio wave based on the radio wave intensity periodically detected for each antenna, and outputs a control signal to receive or transmit the radio wave. Since the antenna to be used is switched, the optimum antenna can be selected according to changes in the communication environment.

  In addition, when the control circuit 8 detects the strength of the radio wave received by the radio circuit 4 while switching the antenna, the control circuit 8 detects the strength of the received radio wave after a predetermined time has elapsed since the high frequency switch 5 switched the connection of the antenna. Thereby, the intensity | strength of an exact received radio wave can be detected for every antenna, and the antenna used for reception or transmission of an electromagnetic wave can be selected appropriately.

(Modification 1)
FIG. 3 shows a circuit configuration of an antenna device 1 </ b> A that is a modification of the antenna device 1. The antenna device 1 </ b> A is different from the antenna device 1 in that the antenna device 1 </ b> A includes a high-frequency switch (first antenna switch) 13 and a high-frequency switch (second antenna switch) 14 instead of the high-frequency switch 11 and the high-frequency switch 12.

  The high-frequency switches 13 and 14 are each configured by a two-terminal switch having one input and one output equivalent to the high-frequency switches 11 and 12, and are provided between the radio circuit 4 and the inverted L-type antenna 2 or the helical antenna 3. The high-frequency switch 13 is provided in a path from the radio circuit 4 to the matching circuit 6 through the ground, in particular, a path from the ground to the matching circuit 6, and opens and closes in conjunction with the switching operation of the high-frequency switch 5. The high-frequency switch 14 is provided in a path from the wireless circuit 4 to the matching circuit 7 via the ground, in particular, a path from the ground to the matching circuit 7, and opens and closes in conjunction with the switching operation of the high-frequency switch 5.

  The operation of the high frequency switches 13 and 14 is the same as that of the high frequency switches 11 and 12. That is, as shown in FIG. 3A, when the high frequency switch 5 connects the radio circuit 4 and the inverted L antenna 2, the radio circuit 4 and the inverted L antenna 2 are closed by closing the radio frequency switch 13. Are electrically connected to each other (route between the ground and the matching circuit 6). Further, when the high frequency switch 14 is opened, the path between the radio circuit 4 and the helical antenna 3 (path between the ground and the matching circuit 7) is electrically cut off.

  On the other hand, as shown in FIG. 3B, when the high frequency switch 5 connects the radio circuit 4 and the helical antenna 3, the high frequency switch 13 is opened so that the radio circuit 4 and the inverted L antenna 2 are connected. Are electrically cut off (route between the ground and the matching circuit 6). Further, when the high frequency switch 14 is closed, the path between the radio circuit 4 and the helical antenna 3 (path between the ground and the matching circuit 7) is electrically connected. That is, since the high frequency switches 13 and 14 operate in conjunction with the high frequency switch 5, the high frequency switch 14 is opened when the high frequency switch 13 is closed, and the high frequency switch 13 is opened when the high frequency switch 13 is opened. The switch 14 is closed.

  According to the antenna device 1 </ b> A, similarly to the antenna device 1, an antenna that is not connected by the high frequency switch 5 can be electrically disconnected from the radio circuit 4 by interlocking the high frequency switch 5 with the high frequency switch 11 and the high frequency switch 12. it can. That is, even if the matching circuits 6 and 7 that cause capacitive coupling or inductive coupling are used, the power feeding path to the antenna not connected by the high frequency switch 5 can be cut off, and the antenna can be switched satisfactorily. In addition, since the above-described effects are obtained by the high frequency switches 13 and 14 provided between the ground and the matching circuit 6 and the matching circuit 7, respectively, the matching circuit 6 and the inverted L-type antenna 2 and the matching circuit are obtained. 7 and the circuit configuration between the helical antenna 3 can be simplified.

(Modification 2)
FIG. 4 shows a circuit configuration of an antenna device 1B that is a modification of the antenna device 1A. The antenna device 1B is an antenna device in that instead of the high-frequency switch 13 and the high-frequency switch 14, a high-frequency switch (first antenna switching path, second antenna switching path) 15 having one input and two outputs equivalent to the high-frequency switch 5 is provided. Different from 1A.

  The high frequency switch 15 opens and closes in conjunction with the high frequency switch 5 to selectively connect either the matching circuit 6 or the matching circuit 7 and the ground. That is, as shown in FIG. 4A, when the high frequency switch 5 connects the radio circuit 4 and the inverted L-type antenna 2, the high frequency switch 15 connects the ground and the matching circuit 6. Thereby, the path between the radio circuit 4 and the inverted L-shaped antenna 2 is electrically connected, and the path between the radio circuit 4 and the helical antenna 3 is electrically cut off.

  On the other hand, as shown in FIG. 4B, when the high frequency switch 5 connects the radio circuit 4 and the helical antenna 3, the high frequency switch 15 connects the ground and the matching circuit 7. Thereby, the path | route between the radio | wireless circuit 4 and the helical antenna 3 is electrically connected, and the path | route between the radio | wireless circuit 4 and the reverse L type | mold antenna 2 is interrupted | blocked electrically.

  According to the antenna device 1B, the antenna that is not connected by the high frequency switch 5 can be electrically disconnected from the radio circuit 4 by the interlocking of the high frequency switch 5 and the high frequency switch 15 as in the antenna device 1A. That is, even if the matching circuits 6 and 7 that cause capacitive coupling or inductive coupling are used, the power feeding path to the antenna not connected by the high frequency switch 5 can be cut off, and the antenna can be switched satisfactorily. In addition, since the above-described effects are obtained by the high-frequency switch 15 provided between the ground and the matching circuit 6 and the matching circuit 7, the operation between the matching circuit 6 and the inverted L antenna 2 and the matching circuit 7 and The circuit configuration with the helical antenna 3 can be simplified. In addition, since a single high-frequency switch 15 can provide the same operational effects as the antenna device 1A, the circuit configuration between the ground and the matching circuit 6 and the matching circuit 7 can be simplified.

  The present invention is not limited to the configuration of the above embodiment. That is, when at least the high-frequency switch 5 connects the radio circuit 4 and the inverted L-type antenna 2, the high-frequency switch 12 opens a path between the radio circuit 4 and the helical antenna 3, and the high-frequency switch 5 is connected to the radio circuit 4. And the helical antenna 3 are connected, the high-frequency switch 11 only needs to be configured to open a path between the radio circuit 4 and the inverted L-type antenna 2.

  The present invention can be modified in various ways. For example, the antenna connected to the matching circuit 6 is an antenna that receives a radio wave transmitted in any polarized wave or transmits a polarized wave. If it is, it will not be restricted to the inverted L type antenna 2. If the antenna connected to the matching circuit 7 is an antenna that receives a radio wave transmitted with a polarization different from any of the above-mentioned polarizations or transmits a radio wave with a polarization, the antenna 3 Not limited to. Further, the configuration of the matching circuit 6 and the matching circuit 7 is not limited to the configuration shown in FIG. In addition, the switch applied to the antenna switching unit, the first antenna switching path, and the second antenna switching path is not limited to a high-frequency switch, and the insertion loss at the time of closing is small and the isolation at the time of opening is sufficiently large. Other types of switches may be used.

1, 1A, 1B Antenna device 2 Inverted L-type antenna (first antenna)
3 Helical antenna (second antenna)
4 Radio circuit 5 High frequency switch (antenna switching part)
6 Matching circuit (first matching circuit)
7 Matching circuit (second matching circuit)
8 Control circuit (Radio wave intensity detection unit, time counting unit)
11 High frequency switch (first antenna switch)
12 High frequency switch (second antenna switch)

Claims (7)

A first antenna that receives a radio wave transmitted in the first polarization or transmits a radio wave of the first polarization;
A second antenna that receives a radio wave transmitted by a second polarization different from the first polarization or transmits a radio wave of the second polarization;
A radio circuit that receives radio waves received by the first antenna or the second antenna or transmits radio waves transmitted by the first antenna or the second antenna;
An antenna switching unit that selectively switches connection between the radio circuit and the first antenna or the second antenna;
A first matching circuit for matching impedance between the first antenna and the radio circuit;
In an antenna device comprising: a second matching circuit that matches impedance between the second antenna and the radio circuit;
A first antenna switching path that is provided in a path from the wireless circuit to the first antenna and opens and closes in conjunction with a switching operation of the antenna switching unit;
A second antenna switching path that is provided in a path from the wireless circuit to the second antenna and opens and closes in conjunction with a switching operation of the antenna switching unit;
When the antenna switching unit connects the radio circuit and the first antenna, the second antenna opening / closing path is opened, and a path between the radio circuit and the second antenna is cut off,
When the antenna switching unit connects the radio circuit and the second antenna, the first antenna switching path is opened to cut off a path between the radio circuit and the first antenna. Antenna device to do. The first antenna switching path is provided in a path from the first matching circuit to the first antenna;
The antenna device according to claim 1, wherein the second antenna switching path is provided in a path from the second matching circuit to the second antenna. The first antenna switching path is provided in a path from the wireless circuit to the first matching circuit,
The antenna device according to claim 1, wherein the second antenna switching path is provided in a path from the wireless circuit to the second matching circuit. The wireless circuit, the first matching circuit, and the second matching circuit are connected via a ground,
The first antenna switching path is provided in a path from the ground to the first matching circuit,
The antenna device according to claim 3, wherein the second antenna switching path is provided in a path from the ground to the second matching circuit.   The antenna device according to claim 3, wherein the first matching circuit and the second matching circuit are configured by a single path switching unit. A radio field intensity detection unit for detecting the radio field intensity received by the wireless circuit;
6. The antenna to which the antenna switching unit is connected when receiving or transmitting a radio wave is selected based on the radio wave intensity detected for each antenna by the radio wave intensity detecting unit. The antenna apparatus as described in any one. A time counting unit for counting time;
An antenna to which the antenna switching unit is connected when receiving or transmitting a radio wave based on the radio wave intensity detected by the radio field intensity detecting unit for each antenna after a predetermined time has elapsed since the antenna switching unit switched the antenna connection. The antenna device according to claim 6, wherein the antenna device is selected.

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