JPH06244756A - Antenna impedance matching device - Google Patents

Abstract

PURPOSE:To match impedance between an antenna and a transmission/reception circuit in transmission/reception bands whose frequencies are separated by providing an impedance matching circuit for transmission/reception and a control part for inputting transmission 7 reception timing signals and switching a switch. CONSTITUTION:The switch 440 is turned on at the time of transmission. A reactance 431 is added in parallel to 431 and the impedance for which the impedance matching circuit 400a and the antenna 300 are looked at from a transmission/reception switching device 500 and the impedance for which the circuit 400a and the switching device 500 are looked at are matched in a transmission frequency band. When the transmission is completed and reception time is started, the switch 440 is turned OFF, the reactance 432 is cut off and the impedance for which the circuit 400a and the antenna 300 are looked at from the switching device 500 and the impedance for which the circuit 400a and the switching device 500 are looked at are matched in a reception frequency band. In such a manner, reception signals are passed through the circuit 400a and sent to the switching device 500 and the impedance is switched to a state where the impedance is matched in both transmission/reception bands.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for both transmission and reception such as time division multiple access (hereinafter referred to as TDMA) type communication and frequency division multiple access (hereinafter referred to as FDMA) type communication provided with an impedance matching circuit. The present invention relates to an antenna impedance matching device.

[0002]

2. Description of the Related Art FIG. 15 is a block diagram showing a conventional antenna impedance matching device. In the figure, reference numeral 100 is a transmitting unit for transmitting, and 200 is a receiving unit for receiving. 300 is an antenna for both transmission and reception, and 400 is an impedance matching circuit for impedance matching of the antenna 300. The impedance matching circuit 400 is composed of fixed reactance elements 410 and 420 connected in series to the antenna 300 and a fixed reactance element 430 placed between the intermediate point and the ground point. Reference numeral 500 denotes a transmission / reception switcher (duplexer) that prevents the transmission signal from the transmission unit 100 from interfering with the impedance matching circuit 400 and the reception signal from the impedance matching circuit 400 with the reception unit 200.

Next, the operation will be described. When transmitting a transmission signal using the antenna impedance matching device, the transmission signal generated by the transmission unit 100 is sent to the impedance matching circuit 400 by the transmission / reception switch 500, and the antenna 300 connected to the impedance matching circuit 400. Sent from. Further, when receiving a reception signal, the reception signal received by the antenna 300 passes through the same impedance matching circuit 400 as at the time of transmission, enters the transmission / reception switch 500, and is transmitted to the reception unit 200.

[0004]

Since the conventional antenna impedance matching device is constructed as described above,
The signal must pass through the same impedance matching circuit with fixed impedance elements regardless of whether it is transmitted or received. FIG. 16 is a diagram showing impedance characteristics according to frequencies when the impedance matching circuit 400 and the antenna 300 are viewed from the transmission / reception switch 500. In FIG. 16, when the X axis is frequency and the Y axis is impedance, the curve Z shows the impedance value. The output impedance of the transmission / reception switch 500 is Z0, the impedance of the reception band fR when the impedance matching circuit 400 and the antenna 300 are viewed from the transmission / reception switch 500 is Z1, and the impedance of the transmission band fT is Z2. As shown in the graph, when the transmission and reception frequency bands are separated, it is very difficult to obtain impedance matching in both frequency bands, and
There is a problem that sufficient antenna gain cannot be obtained because impedance matching between the antenna and the transmission / reception circuit (transmission / reception switch) cannot be obtained.

The present invention has been made in order to solve the above problems, and impedance matching between an antenna and a transmission / reception circuit (transmission / reception switch) is performed in both transmission and reception frequency bands with different frequencies. With the goal.

[0006]

An antenna impedance matching device according to a first aspect of the present invention comprises an impedance matching means which is connected to an antenna and has a switch for switching between impedances for transmission and reception, and inputting a transmission / reception timing. A control means for switching the switch is provided so as to match the impedances of the antenna and the impedance matching means.

In the antenna impedance matching device according to a second aspect of the present invention, the impedance matching means is provided between two series reactances connected in series to the antenna and an intermediate connection point between the two series reactances and the ground. A switch for switching between the two branch reactances is provided, and the branch switch is switched by a control signal from the control means.

In the antenna impedance matching device according to a third aspect of the present invention, the impedance matching means includes one variable reactance provided between an intermediate connection point of two series reactances connected in series to the antenna and the ground. It is included.

An antenna impedance matching device according to a fourth aspect of the present invention is an impedance matching means connected to an antenna and adapted to be switched by a switch so as to match the impedance to the antenna during transmission and reception, and a received signal connected to the impedance matching means. The interfering radio wave removal filter for releasing the interfering radio wave contained in the earth to the ground, the filter opening switch for disconnecting the interfering radio wave removal filter, and the above-mentioned antenna and impedance matching means to match the impedance by inputting the transmission / reception timing. A control means for switching the switch and opening the filter opening switch at the time of transmission is provided.

According to a fifth aspect of the present invention, there is provided an antenna impedance matching device, wherein impedance matching means is connected to the antenna so that impedances in frequency bands separated by transmission and reception can be switched by a switch, and a received signal connected in series with the antenna. The interfering radio wave removal filter for blocking the interfering radio wave included in the above, a filter short-circuit switch for short-circuiting the interfering radio wave removal filter, and the above-mentioned antenna so as to match the impedance of the impedance matching means by inputting the transmission / reception timing. A control means is provided for switching the switch and for short-circuiting the filter short-circuit switch during transmission.

According to a sixth aspect of the present invention, there is provided an antenna impedance matching device, wherein the impedance matching means is switched by a signal from a control means connected in series to the antenna, and a transmitter connected in series to each switch. The impedance matching means and the receiving impedance matching means are included.

[0012]

In the impedance matching circuit of the antenna impedance matching device according to the first aspect of the present invention, the impedance is switched for transmission during transmission and for reception during reception by a switch controlled by the control unit, and both frequencies for transmission and reception are provided. Impedance matching is performed between the antenna and the transmitting / receiving circuit in the band.

In the impedance matching circuit of the antenna impedance matching device according to the second aspect of the present invention, the transmission / reception timing is input for transmission during transmission and reception for reception, and the branch reactance is switchably connected to the switch by the control unit. Also, the impedance matching between the antenna and the impedance matching means is performed in both the transmitting and receiving frequency bands by controlling the switch.

In the impedance matching circuit of the antenna impedance matching device according to the third aspect of the present invention, the transmission / reception timing is input for transmission during transmission and for reception during reception, and the variable reactance is controlled by the output of the control unit to perform transmission / reception. Impedance matching is performed between the antenna and the impedance matching means in both reception frequency bands.

The impedance matching means of the antenna impedance matching device according to the invention of claim 4 can switch impedances for transmission during transmission and for reception during reception by a switch controlled by the control unit, and both frequencies for transmission and reception. Impedance matching is performed between the antenna and the impedance matching means in the band. In addition, the control unit releases an interfering radio wave included in the received signal to the earth by the interfering radio wave removal filter in series with the filter open switch provided in the impedance matching circuit at the time of reception, and opens the filter open switch at the time of transmission to open the interfering radio wave removal filter. Control to disconnect.

The impedance matching means of the antenna impedance matching device according to the fifth aspect of the present invention can switch the impedance for transmitting at the time of transmitting and for receiving at the time of receiving by the switch controlled by the control unit, and both frequencies for transmitting and receiving. Impedance matching is performed between the antenna and the impedance matching means in the band. Further, the control unit has a filter provided in parallel with the interference wave removal filter so that the interference wave removal filter provided in series with the antenna blocks the interference wave included in the received signal at the time of reception and short-circuits the interference wave removal filter at the time of transmission. Control to close the short-circuit switch.

In the two impedance matching circuits for transmission and reception of the antenna impedance matching device according to the sixth aspect of the present invention, the timing of transmission and reception is input to the impedance matching circuit for transmission at the time of transmission and the impedance matching circuit for reception at the time of reception. The impedance matching circuit is controlled by the control unit by switching the impedance matching circuits to achieve impedance matching between the antenna and the impedance matching means in both the transmission and reception frequency bands.

[0018]

EXAMPLES Example 1. 1 is a block diagram of an antenna impedance matching device according to an embodiment of the present invention. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numerals 100, 200, 300 and 500 are the same as or equivalent to those of the conventional example shown in FIG. Reference numeral 400a denotes an impedance matching circuit for impedance matching between the antenna 300 and the transmission / reception switch 500, which can be switched between transmission and reception during transmission and reception. The impedance matching circuit 400a constitutes a T-shaped matching circuit, and the antenna 3
In series with 00, inductances 410 and 420 and a connection point between them are connected to a capacitance 431 between grounds, and a capacitance 432 is connected to a ground by a switch 440 so as to be openable and closable. Here, in the TDMA method, it is necessary to switch transmission / reception at a speed of several tens of times per second, so that the switch 440 has a fast response speed, for example, PIN.
It uses a diode. Reference numeral 600a denotes a control unit that inputs transmission / reception timing from a TDMA slot and switches the impedance matching circuit 400a (internal switch 440) between the antenna 300 and the transmission / reception units 100 and 200. A control signal for switching the impedance matching circuit 400a between the circuits for transmission during transmission and for reception during reception is output.

Next, the operation will be described. When transmitting the transmission signal, the transmission signal generated by the transmission unit 100 is
Impedance matching circuit 40 through transmission / reception switch 500
Sent to 0. At the same time, the control unit 600a inputs that transmission is in progress from the TDMA slot, and sends a control signal to the impedance matching circuit 400a between the antenna and the transmission / reception circuit. The impedance matching circuit 400a receives this control signal and switches to the transmission mode. The transmission signal that has passed through the impedance matching circuit 400a that has been switched for transmission has the antenna 30 in the impedance-matched state.
Sent from 0.

When receiving a received signal, the antenna 300
The received signal received by the antenna 300 and the transmitter / receiver 1
It is sent to the impedance matching circuit 400a between 00 and 200. At the same time, the control unit 600a inputs that it is receiving from the TDMA slot, and the impedance matching circuit 40 between the antenna 300 and the transmission / reception units 100 and 200 is input.
Send a control signal to 0a. The impedance matching circuit 400a receiving this is switched for reception. The received signal that has passed through the impedance matching circuit 400a switched for reception is the antenna 300 and the transmission / reception units 100, 200.
The transmission / reception switch 50 with impedance matching between
0 to the receiving unit 200.

Next, the operation of the impedance matching circuit 400a will be described with reference to the drawings. A box 400a in FIG. 1 is an example of the impedance matching circuit 400a. When sending,
The aforementioned control signal becomes H, and the switch 440 is turned on. The reactance 432 is added in parallel to the reactance 431. By adding the reactance 432 in parallel, the impedance of the impedance matching circuit 400a and the antenna 300 seen from the transmission / reception switching device 500, the impedance matching circuit 400a, and the transmission / reception switching device 50.
The impedance at 0 is matched in the transmission frequency band. When the transmission is completed and the reception is started, the control signal becomes L, and the switch 440 is turned OFF. At this time, the reactance 432 connected in parallel is disconnected, so that the impedance of the impedance matching circuit 400a and the antenna 300, and the impedance of the impedance matching circuit 400a and the impedance of the duplexer 500 are separated from the transmission / reception switcher 500. It becomes a matched state in the reception frequency band. In this way, the received signal passes through the impedance matching circuit 400 and is sent to the duplexer 500. By doing so, the impedance can be switched to a state in which the impedance is matched with the transmission / reception band.

The above operation is performed from the frequency pair transmission / reception switch 500 to the impedance matching circuit 400a and the antenna 300.
The impedance will be described with reference to the figure. 2 and 3 show a frequency versus transmission / reception switch 5 at the time of transmission and reception.
It is a figure which shows the impedance which looked at the impedance matching circuit 400a and the antenna 300 from 00. 2, 3
In the case where the X axis is frequency and the Y axis is impedance, curves R and T show impedance values. The solid line indicates the impedance matching circuit 40.
0a shows the antenna impedance value when the impedance is switched to transmission or reception. The dotted line is the case in the conventional example. That is, in FIG. 2, the impedance of the transmission / reception switch 500 when the impedance matching circuit 400a and the antenna 300 are viewed is Z0, and the transmission band frequency when the impedance matching circuit 400a and the antenna 300 are viewed from the transmission / reception switch 500 at the time of transmission. The impedance value at fT is outside Z0, and the impedance value at the reception band frequency fR is outside Z0.

Further, at the time of reception, the impedance of the transmission / reception switching device 500 as seen from the impedance matching circuit 400a and the antenna 300 in FIG. 3 is Z0, and the impedance matching circuit 400a from the transmission / reception switching device 500 at the time of reception.
Looking at the antenna 300, the impedance value at the reception band frequency fR is outside Z0, and the impedance value at the transmission band frequency fT is outside Z0. The antenna impedance value is also Z0, the impedance value at the reception band frequency fR of the impedance matching circuit 400a at the time of reception is Z0, and the impedance value at the transmission band frequency fT is outside Z0. As described above, the impedance matching circuit 400a and the antenna 300 are switched from the transmission / reception switch 500 in the target transmission or reception states.
The impedance value seen is always kept at Z0.

Next, the specific operation of the controller 600a will be described. FIG. 4 is a flowchart showing the operation of the control unit 600a. In FIG. 4, the control unit 600a has a TD
Check whether the MA slot is the timing of transmission.
At the transmission timing, the control unit 600a outputs a control signal for switching the impedance matching circuit 400a to the transmission side. When it is not the transmission timing, the control unit 600
a checks whether the TDMA slot is the reception timing, and outputs a control signal for switching the impedance matching circuit 400a to the reception side at the reception timing. Repeat the above series of operations until the call ends,
At the end of the call, a control signal for switching the impedance matching circuit 400a to the receiving side is output in order to enter the standby state.

FIG. 5 is a timing chart showing the relationship between the transmission / reception timing of the TDMA slot during a call and the control signal. In FIG. 5, if the transmission timing of the TDMA slot is (H), the control signal is output (H), and if the reception timing is (H), the control signal is not output (L).

Example 2. FIG. 6 is a block diagram of only the impedance matching circuit of the antenna impedance matching device according to the first exemplary embodiment of the present invention. In FIG. 6, 400b is an impedance matching circuit.
α is an antenna connection terminal, 400β is a transmission / reception switch connection terminal, and 400γ is a control input. 450 and 451 are series reactances, 452 and 453 are branch reactances connected thereto, and 454 is this branch reactance 4
A switch for switching 53 according to transmission and reception.

In operation, the impedance matching circuit 400b is switched by the switch 454 for transmission only during transmission and for reception only during reception by a control input from a control unit (not shown). In this embodiment, the branch reactance 453 is switched by short-circuiting with the switch 454.

FIG. 7 is a block diagram of only the impedance matching circuit of the antenna impedance matching device according to the second embodiment of the present invention. In FIG. 7, 400
Since α, 400β, 400γ, 450, and 451 are the same as those in FIG. 6, description thereof will be omitted. 400c is an impedance matching circuit, 456 and 457 are branch reactances connected to the series reactances 450 and 451, and 455 is a switch for switching these branch reactances 456 and 457 according to transmission and reception.

The operation of the impedance matching circuit 400c is switched by the switch 455 for transmission only during transmission and for reception only during reception by a control input from a control unit (not shown).

FIG. 8 is a block diagram of only the impedance matching circuit of the antenna impedance matching device according to the third embodiment of the present invention. In FIG. 8, 400
Since α, 400β, 400γ, 450, and 451 are the same as those in FIG. 6, description thereof will be omitted. 400d is an impedance matching circuit, 458 and 459 are branch reactances connected to the series reactances 450 and 451, and 454 is a switch for switching this branch reactance 459 according to transmission and reception.

To explain the operation, the impedance matching circuit 400d is switched by the switch 454 for transmission only during transmission and for reception only during reception by a control input from a control unit (not shown). In this embodiment, the impedance of the impedance matching circuit 400d is switched by opening the branch reactance 459 with the switch 454.

Example 3. FIG. 9 is a block diagram of an antenna impedance matching device according to an embodiment of the invention of claim 3, wherein a variable reactance for varying reactance is used in an impedance matching circuit, and the impedance characteristic of the variable reactance is changed by a control signal from a control unit. Impedance matching. In FIG. 9, 100, 200, 300, 410, 420, 43
Reference numerals 1 and 500 are the same as or equivalent to those in FIG. 400e is an impedance matching circuit including a variable capacitance diode 433 as a variable reactance, 460 is a choke coil, and 600d is a control unit that applies a bias voltage to the variable capacitance diode 433 through the choke coil 460 to control the capacitance to a required value. .

The control signal from the control section 600d is a DC voltage for controlling the variable capacitance diode 433 to a target impedance, and this DC voltage is applied as a bias voltage. In this embodiment, the control unit 6 controls the variable capacitance diode 433 to indicate the capacitance value required for impedance matching even when a large number of transmission and reception frequency bands are applied.
Since the control signal from 00d is used as the DC voltage and is applied as the bias voltage of the variable capacitance diode 433, the circuit configuration and control are simple as compared with the method of switching the impedance element by a large number of diode switches.

Next, the operation will be described.
The above-mentioned control signal becomes H as shown in FIG. 5, and the reactance value of the variable capacitance diode 433 is changed. The transmission signal is sent to the antenna 300 through the impedance matching circuit 400e in which the impedance between the antenna and the transmission / reception circuit is changed. When transmission is completed and reception is started, the control signal becomes L as shown in FIG. 5, and the reactance value of the variable capacitance diode 433 becomes different from that at the time of transmission. At this time, the received signal is sent to the duplexer 500 through the impedance matching circuit 400e whose impedance has changed from the transmitting state. By doing so, the impedance of the impedance matching circuit 400e can be switched during transmission and reception.

Example 4. FIG. 10 is a block diagram of an antenna impedance matching device according to an embodiment of the present invention. First, the background of the present invention will be described. For example,
2. Description of the Related Art In a receiving device dedicated to reception such as a television relay broadcasting device, a notch filter that matches the frequency of an interfering radio wave is often provided between an antenna and the receiving device to remove an interfering radio wave included in a reception signal of a fixed frequency. However, since this notch filter inevitably disturbs the impedance at the notch frequency, if it is used as it is by switching transmission and reception as in the present application, if the interfering radio waves happen to be close to the transmission frequency or match the transmission frequency, the transmission band of the transmission band It will disturb the impedance and will not be usable. Therefore, a notch filter (interfering radio wave elimination filter) that disturbs impedance during transmission is separated by a switch to eliminate the influence. In FIG. 10, 100, 200, 300, 400a, 420, 4
Reference numerals 31, 432, 440, and 500 are the same as or equivalent to those in FIG. 600b is
The transmission / reception timing is input from the TDMA slot, and the impedance matching circuit 400a between the antenna 300 and the transmission / reception units 100 and 200 (the internal switch 4 is used).
40) and a control unit for controlling switching of a later-described interference wave removal filter, 700a is an inductance 7
01, 702 and a capacitance 703, for example, a notch filter, 7
Reference numeral 10 is a filter opening switch that disconnects the notch filter 700a during transmission. Note that the inductance 70
Since 2 is always inserted, the inductance 41
0a is obtained by subtracting the inductance value by a smaller amount than the inductance 410 of FIG.

Next, the operation will be described. At the time of transmission, the control unit 600b inputs the transmission / reception timing from the TDMA slot, and the antenna 300 and the transmission / reception unit 10
The impedance matching circuit 400a (the internal switch 440) is switched between 0 and 200 and the filter opening switch 710 is controlled to be disconnected.
00 impedance matching is performed correctly. At the time of reception, the control unit 600b inputs the transmission / reception timing from the TDMA slot, and the antenna 300 and the transmission / reception unit 10 receive.
The impedance matching circuit 400a (the internal switch 440) is switched between 0 and 200 and the filter opening switch 710 is connected to control the notch filter 700a so that the impedance matching circuit 400a is connected to the impedance matching circuit 400a.
And the impedance of the transmission / reception switcher 500 are matched, and the interference wave included in the received signal is removed by the function of the notch filter 700a.

The above operation is performed from the frequency pair transmission / reception switch 500 to the impedance matching circuit 400a and the antenna 300.
The impedance will be described with reference to the figure. Figure 1
1 and 12 are from the frequency pair transmission / reception switch 500 at the time of transmission and at the time of reception, respectively, to the impedance matching circuit 400a.
It is a figure which shows the impedance which looked at and the antenna 300. 11 and 12, curves Z, T, and RN show impedance values when the notch filter operates at the time of transmission and when the notch filter at the time of reception, respectively, when the frequency is plotted on the X axis and the impedance is plotted on the Y axis. Notch filter 700 during transmission
Since a is separated, it has no relation to the circuit, and is similar to that shown in FIG. 2 (curve T). That is, the notch open switch 710 operates so that the notch filter 700a is disconnected from the circuit, and the impedance value becomes Z0 as shown by the curve T, and impedance matching is achieved. Therefore, even if the interference frequency is included in the transmission frequency band here, the impedance value is not affected because the notch filter 700a is disconnected from the circuit.

In FIG. 11, a transmission / reception switch 50 is used for transmission.
0 to impedance matching circuit 400a and antenna 30
The impedance at 0 is out of Z0 at the reception band frequency fR, but Z at the transmission band frequency fT.
The impedance value at the transmission band frequency fT is prevented from deviating from Z0 by disconnecting the notch filter 700a. As described above, the impedances of the transmission band during transmission and the reception band during reception when the impedance matching circuit 400a and the antenna 300 are viewed from the transmission / reception switcher 500 are always maintained at Z0 in the target transmission or reception states.

In FIG. 12, the impedance of the transmission / reception switch 500 seen from the impedance matching circuit 400a at the time of reception is Z0, and the reception band frequency of the impedance matching circuit 400a and the antenna 300 seen from the transmission / reception switch 500 at the time of reception. The impedance value at fR is Z0,
The impedance value at the transmission band frequency fT is out of Z0. At this time, fN is the frequency of the notch filter and the interference radio wave of the frequency of the notch filter is released to the ground, so the impedance value becomes close to 0 at that frequency. The impedance value at the transmission band frequency fT deviates from Z0, but at the time of reception, if only the impedance in the reception band is Z0, there is no adverse effect. As described above, the impedances of the transmission band during transmission and the reception band during reception when the impedance matching circuit 400a and the antenna 300 are viewed from the transmission / reception switcher 500 are always maintained at Z0 in the target transmission or reception states.

Example 5. FIG. 13 is a block diagram of an antenna impedance matching device according to an embodiment of the invention of claim 5, and the antenna impedance matching device according to the embodiment 4. An interfering radio wave removal filter that blocks the interfering radio wave contained in the received signal of is installed in series with the above antenna, and at the time of transmission, the interfering radio wave removal filter is short-circuited by a switch to eliminate its influence. Is. In FIG. 13, 100, 20
0, 300, 400a, 410, 420, 431, 43
Reference numerals 2, 440 and 500 are the same as or equivalent to those in FIG. 600c inputs transmission / reception timing from a TDMA slot, switches the impedance matching circuit 400a (the internal switch 440) between the antenna 300 and the transmission / reception units 100 and 200, and short-circuits an interference wave elimination filter described later. A control unit for controlling disconnection, 700b is an inductance 7
04 and capacitances 705 and 706, for example, a notch filter, 7
Reference numeral 11 is a filter short-circuit switch that short-circuits the notch filter 700a during transmission and disconnects it in a circuit manner. Reference numeral 712 is a switch that disconnects the capacitance 706, which is a part of the circuit element of the notch filter 700a, during circuit transmission.

Next, the operation will be described. At the time of transmission, the control unit 600c inputs the transmission / reception timing from the TDMA slot, and the antenna 300 and the transmission / reception unit 10
The impedance matching circuit 400a controls the switching between the impedance matching circuit 400a (switch 440 inside) and the filter short-circuiting switch 711 so that the switch 712 is disconnected. Correct alignment. During reception, the control unit 600c inputs the transmission / reception timing from the TDMA slot, switches the impedance matching circuit 400a (internal switch 440) between the antenna 300 and the transmission / reception units 100 and 200, and opens the filter short-circuit switch 711. Switch 71
Since the notch filter 700b is connected to the impedance matching circuit 400a so as to be connected to the impedance matching circuit 400a, the impedance matching circuit 400a correctly performs impedance matching between the antenna 300 and the duplexer 500, and the interference wave included in the received signal. Is blocked by the notch filter 700b and does not reach the duplexer 500.

Example 4.5. In the above, even if a band stop filter (not shown) is provided in place of the notch filter that needs to be provided with a notch according to the frequency of the interfering signal, the same operation is performed. When there are a few interfering signal frequencies, a notch filter with better attenuation performance at the pinpoint frequency that matches the frequency is generally preferable to a band elimination filter, but when there are multiple interfering signal frequencies, they should be combined in a band that covers them. It is convenient to configure with a band elimination filter that can be eliminated because the configuration is simple.

Example 6. FIG. 14 shows an embodiment of the invention of claim 6 in which dedicated impedance matching circuits for transmitting and receiving are provided and switched by switches. In this case, a dedicated impedance matching circuit can be provided even if the impedance matching circuit is connected to an antenna exhibiting an arbitrary impedance in the transmission / reception frequency band, so that the design is simple compared to the case where the impedance matching circuit is also used for transmission / reception.

In FIG. 14, 400f is a control section 600a.
A switch 490 which is switched by a control signal from
Three fixed reactance elements 460T, 470T, 48
Impedance matching circuit 400g consisting of 0T
And three fixed reactance elements 460R, 470R,
Impedance matching circuit 400 for reception comprising 480R
It is an impedance matching circuit including h. Reference numeral 500a denotes a transmission filter 510 and a reception filter 5 described below.
It is a transmission / reception switching device consisting of 20. Reference numeral 520 is a reception filter 510 is a transmission filter, and 520 is a reception filter, which passes only the transmission frequency and the reception frequency, respectively.

At the time of transmission, the above-mentioned control signal becomes H as shown in FIG. 5, and the switch 490 is switched to the transmission impedance matching circuit 400g side. The transmission signal is sent to the antenna 300 through the transmission impedance matching circuit 400g. Upon completion of transmission and reception, the control signal becomes L as shown in FIG. 5, and the switch 490 switches to the receiving impedance matching circuit 400h side. The reception signal passes through the reception impedance matching circuit 400h and is sent to the reception filter 520. By doing so, it is possible to switch between the transmission impedance matching circuit 400g and the reception impedance matching circuit 400h. Then, even if the reception signal disappears, the control signal remains L, and the switch 490 operates as the reception impedance matching circuit 4
It remains switched to the 00h side, and enters the standby state.

Further, even if there is no transmission signal from the transmission state, the control signal remains L, the switch 490 is still switched to the receiving impedance matching circuit 400h side, and is in the standby state. By doing so, the impedance matching elements 460R, 470R, 48 are received during reception.
0R is used, and the impedance matching element 46 is used during transmission.
Switching is performed using 0T, 470T, and 480T.

Then, in this Embodiment 6. When an undesired radio wave removing filter (not shown) is provided in FIG. 4, it may be left connected to the receiving impedance matching circuit 400h side. No filter open switch or filter short circuit switch shown in FIG. In this case, naturally, the values of the elements of the impedance matching circuit 400h are determined so that the impedance matching is performed with the interference wave elimination filter provided.

The case where the present invention is applied to the TDMA type transceiver has been described above. However, the present invention is not limited to this and can be applied to the case where it is necessary to quickly perform impedance matching over a wide frequency range even for transmission or reception only. It goes without saying that you can demonstrate In this case, the frequency for which impedance matching is to be performed and its frequency switching timing are input to the control unit, and the impedance matching unit is controlled to perform impedance matching with the transmitter or receiver connected to the impedance matching unit. be able to.

Further, the impedance matching between the antenna and the impedance matching circuit has been described under the condition that the impedance on the transmission / reception switch side is constant, but the impedance of the transmitter and the receiver is not constant but changes in a wide frequency band. This can also be dealt with by setting the circuit constant of the impedance matching circuit so that the impedance is matched when the switch is switched. Further, the transmission and reception bands may be plural instead of one band or may overlap each other.

[0050]

As described above, according to the first aspect of the present invention, the impedance matching means connected to the antenna so that the impedance can be switched by the switch and the timing signal for transmission / reception are input to the switch. Since the impedance is switched by providing the control means for switching the impedances, there is an effect that impedance matching can be perfectly achieved in both frequency bands even if the frequency bands for transmission and reception are separated.

According to a second aspect of the present invention, the impedance matching means is provided between two series reactances connected in series to the antenna and an intermediate connection point between the two series reactances and the ground. A switch for switching between the two branched reactances is provided, and the branch reactance is switched by switching the switch according to a signal from the control means.
There is an effect that impedance matching can be perfectly achieved in both frequency bands even if the reception frequency bands are separated.

According to the third aspect of the invention, the reactance connected in series to the antenna of the impedance matching means and one variable reactance provided between the midpoint of the reactance and the ground. Since the impedance value is controlled by the control signal of the control unit, there is an effect that impedance matching can be achieved in a plurality of frequency bands even if the transmission and reception frequency bands are separated.

According to the invention described in claim 4, there are provided an impedance matching means connected to the antenna so that the impedance can be switched by a switch, and a control means for switching the switch by inputting a transmission / reception timing signal. Since the impedance is switched in preparation, perfect impedance matching can be achieved in both frequency bands even if the transmission and reception frequency bands are separated, and the interference wave elimination filter is opened by the control means during transmission. Since the filter is opened by the filter open switch, there is an effect that the interference radio wave included in the received signal at the time of reception can be released to the ground by the interference wave removal filter without affecting the impedance matching at the time of transmission.

According to the fifth aspect of the present invention, impedance matching means connected to the antenna so that impedances in frequency bands separated from each other for transmission and reception can be switched by a switch, and reception means connected in series with the antenna. An interference wave elimination filter that blocks the interference wave included in the signal, a filter short-circuit switch that short-circuits this interference wave elimination filter, and the impedance of the antenna and the impedance matching means are matched by inputting the transmission / reception timing. Since the control means for switching the switches and short-circuiting the filter short-circuiting switch at the time of transmission is provided, impedance matching can be perfectly achieved in both frequency bands even when the frequency bands for transmission and reception are separated. When using an interference filter Since it is short-circuited by the filter short-circuit switch, the interference wave included in the received signal at reception is blocked by the interference wave removal filter inserted in series in the antenna without causing impedance disturbance and loss by the interference wave removal filter at transmission. There is an effect that can be done.

According to the sixth aspect of the invention, the impedance matching means is a switch which is switched by a signal from the control means connected in series to the antenna,
By switching the impedance matching means for transmission and the impedance matching means for reception connected in series to this switch by controlling the antenna switching means, even if the transmission / reception frequency bands are separated and the antenna impedance is significantly different. Since impedance matching means can be provided for each of the transmission and reception bands, there is an effect that impedance matching can be perfectly achieved in both frequency bands.

[Brief description of drawings]

FIG. 1 is a block diagram showing an antenna impedance matching device according to an embodiment of the present invention.

FIG. 2 shows an impedance matching circuit 400a and an antenna 300 from a frequency pair transmission / reception switch 500 during transmission.
It is a figure which shows the impedance which looked at.

FIG. 3 shows an impedance matching circuit 400a and an antenna 300 from a frequency pair transmission / reception switch 500 during reception.
It is a figure which shows the impedance which looked at.

FIG. 4 is a flowchart illustrating an operation of the control unit 6 of the present invention.

FIG. 5 is an example of a timing chart showing TDMA slot transmission / reception timings and control signals.

FIG. 6 is a block diagram showing an antenna impedance matching device according to an embodiment of the invention of claim 2;

FIG. 7 is a block diagram showing an antenna impedance matching device according to an embodiment of the invention of claim 2;

FIG. 8 is a block diagram showing an antenna impedance matching device according to an embodiment of the invention of claim 2;

FIG. 9 is a block diagram showing an antenna impedance matching device according to an embodiment of the invention of claim 3;

FIG. 10 is a block diagram showing an antenna impedance matching device according to an embodiment of the invention of claim 4;

FIG. 11 is a diagram showing impedances when the impedance matching circuit 400a and the antenna 300 are viewed from the frequency pair transmission / reception switch 500 during transmission according to the embodiment of the invention of claim 4;

FIG. 12 is a diagram showing impedances when the impedance matching circuit 400a and the antenna 300 are seen from the frequency pair transmission / reception switch 500 at the time of reception of the embodiment of the invention of claim 4;

FIG. 13 is a block diagram showing an antenna impedance matching device according to an embodiment of the invention of claim 5;

FIG. 14 is a block diagram showing an antenna impedance matching device according to an embodiment of the invention of claim 6;

FIG. 15 is a block diagram showing a conventional antenna impedance matching device.

FIG. 16 is a diagram showing antenna impedance versus frequency during transmission and reception of a conventional antenna impedance matching device.

[Explanation of symbols]

400a, 400b, 400c, 400d, 400e,
400f Impedance matching circuit 400g Transmission impedance matching circuit 400h Reception impedance matching circuit 410, 420, 431, 432, 458, 459, 4
60T, 460R, 470T, 470R, 480T, 4
80R reactance element 433 variable capacitance diode 440, 454, 455, 490, 712 switch 450, 451 series reactance element 452, 453, 456, 457 branch reactance element 500, 500a, transmission / reception switcher 600a, 600b, 600c, 600d control section 700a , 700b Notch filter 710 Filter open switch 711 Filter short-circuit switch

Claims (6)

[Claims] 1. An impedance matching means, which is connected to an antenna and is switched by a switch so that impedance is matched to the antenna for transmission and reception, and impedance of the antenna and the impedance matching means are matched by inputting timing of transmission and reception. An antenna impedance matching device comprising a control means for switching the above switch. 2. The impedance matching means includes a switch for switching between two series reactances connected in series to the antenna and two branch reactances provided between an intermediate connection point of the two series reactances and a ground. The antenna impedance matching device according to claim 1, further comprising: a switch for switching the switch according to a signal from the control means. 3. The impedance matching means includes two reactances connected in series to an antenna and one variable reactance provided between an intermediate connection point of these two reactances and a ground. The antenna impedance matching device according to claim 1. 4. An impedance matching means which is connected to an antenna and is switched by a switch so as to match the impedance to the antenna during transmission and reception, and an interference radio wave contained in the received signal which is connected to the impedance matching means and escapes to the ground. An interference wave elimination filter, a filter opening switch for separating the interference wave elimination filter, and switching of the switch so as to match the impedance of the antenna and the impedance matching means by inputting the transmission / reception timing, and the filter opening switch at the time of transmission. An antenna impedance matching device, characterized in that a control means for opening the circuit is provided. 5. An impedance matching means connected to an antenna so that impedances in frequency bands separated from each other for transmission and reception can be switched by a switch, and interference for blocking interference radio waves included in a reception signal connected in series with the antenna. A radio wave elimination filter, a filter short circuit switch for short-circuiting the interference radio wave elimination filter, and switching of the switch so as to match the impedance of the antenna and the impedance matching means by inputting the transmission / reception timing, and the filter short circuiting switch at the time of transmission. An antenna impedance matching device, characterized in that control means for short-circuiting is provided. 6. The switch, wherein the impedance matching means is switched by a signal from the control means connected in series to the antenna, the transmission impedance matching means and the reception impedance matching means respectively connected in series to the switch. The antenna impedance matching device according to claim 1, comprising: