JPH11251956A - Antenna matching adjustment circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimally adjust impedance in a respective transmission state and a reception state in an antenna matching adjustment circuit and to perform efficient communication. SOLUTION: A detection circuit 17 is connected to a circulator 15 provided between a variable type matching adjustment circuit 14 and a transmission/ reception changeover circuit 16. The detection circuit 17 detects the level of transmission reflected waves reflected in the variable type matching adjustment circuit 14 at the time of transmission, detects the level of reception waves at the time of reception and outputs it to a control part 9. The control part 9 outputs control data to a D/A converter and controls the constant of the variable type matching adjustment circuit 14 so as to minimize the transmission reflected waves at the time of the transmission and to maximize the reception waves at the time of the reception based on the output of the detection circuit 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna matching circuit, and more particularly to an antenna matching adjusting circuit which uses a variable matching circuit to automatically and automatically set circuit constants in a transmission state and a reception state.

[0002]

2. Description of the Related Art Conventionally, a radio device has a matching circuit provided between an antenna and a transmission / reception switching unit for the purpose of matching impedance between the antenna and the radio circuit.
As such a matching circuit, a circuit configured to switch its circuit constant based on a received signal level or perform variable adjustment control so that communication can be performed with appropriate impedance in reception and transmission is proposed. (Japanese Unexamined Patent Publication Nos. 7-111470, 8)
JP-A-130493, JP-A-9-69799).

FIG. 7 is a block diagram showing a configuration example in which an example of the matching circuit described in the above publication is applied to a portable wireless device. Antenna matching circuit 2 connected to antenna 1
The circulator 3 is provided in the
In addition, a transmission / reception circuit configuration in which a radio reception unit 5 and a radio transmission unit 6 are connected via a directional coupling unit 4 is adopted. Further, a monitor receiver 7 is connected to the directional coupling unit 4, and the monitor receiver 7 outputs signal level information to the control unit 7. The control unit 9 has a configuration for adjusting the antenna matching circuit 2 based on the information on the signal level from the monitor receiver 7. The control unit 9 controls the input / output of the baseband such as the audio signal related to the receiver 12 and the transmitter 13 between the wireless receiving unit 5 and the wireless transmitting unit 6, and is stored in the storage unit 8. AL of the wireless transmission unit 6
Control such as controlling the C circuit to keep the gain for the transmission signal constant is performed.

In the portable radio shown in FIG. 7, a high-frequency transmission signal from a radio transmission section 6 is transmitted from an antenna 1 via a circulator 3 and an antenna matching circuit 2 by a transmission / reception isolation function of a circulator 3, and the antenna 1 Is configured to be received by the wireless receiver 5 via the circulator 3 and the directional coupler 4.

[0005] The transmission signal output from the radio transmission unit 6 is:
The signal is output to the antenna via the circulator 3. Further, the circulator 3 has a characteristic that a transmission signal from the wireless transmission unit 6 partially leaks to the wireless reception unit 5 side,
The reception signal and the leaked transmission signal are simultaneously output to the wireless receiver of the circulator 3 in a mixed state. Directional coupling part 4
Has a function of outputting a reception signal to a wireless reception unit and separating and outputting the leaked transmission signal to a monitor receiver 7. The monitor receiver 7 detects the signal level of the leak signal and outputs it to the control unit 9. The control unit 9 receives the detection signal of the signal level, and controls the constant of the antenna matching circuit 2 based on the detection signal so that the leaked transmission signal level is minimized.

As described above, in the portable radio shown in FIG. 7, the impedance of the antenna matching circuit 2 in the reception and transmission in the radio receiver 5 and the radio transmitter 6 is determined by the transmission signal leaked to the reception path due to the characteristics of the circulator itself. By controlling, the receiving characteristic is adjusted. The portable wireless device operates so that the antenna matching circuit 2 is automatically adjusted when transmission and reception are performed simultaneously.

[0007]

In the prior art, the antennas in the transmission and reception states are matched by using the transmission signal leaking to the reception path due to the characteristics of the circulator. Could not be optimized.

In addition, the conventional antenna matching adjustment circuit is a radio device whose transmission / reception characteristics are easily affected by the surrounding environment.
For example, there is a difficulty in applying the present invention to a portable wireless device or the like in which the surrounding environment of the antenna changes frequently due to the approach of a human body or a metal object.

Furthermore, when the present invention is applied to a portable radio having a wide operating frequency band such as having a plurality of channels, a small antenna having a narrow band characteristic of the portable radio cannot sufficiently cover a transmission / reception band. However, there is a problem in matching characteristics for a simple antenna.

Further, since the monitor receiver has a configuration that is always connected to the high-frequency signal circuit, there is a problem in improving the receiving sensitivity.

(Object of the Invention) An object of the present invention is to provide an antenna matching adjustment circuit which can adjust the impedance optimally in each of the transmission state and the reception state, and enables efficient communication. is there.

It is another object of the present invention to provide an antenna matching adjustment circuit which can individually adjust transmission and reception bands and make matching characteristics to an antenna close to a reception frequency.

Another object of the present invention is to provide an antenna matching adjustment circuit capable of improving reception sensitivity.

[0014]

An antenna matching adjustment circuit according to the present invention comprises a variable matching section connected to an antenna, a transmission / reception switching section connected to a radio reception section and a radio transmission section, and the variable matching section. And a detection circuit that is connected between the transmission / reception switching unit and detects a transmission reflected wave level from the variable type matching unit side during transmission and a reception wave level during reception, based on an output of the detection circuit. A control unit for controlling a circuit constant of the variable matching circuit.

Further, the antenna matching adjustment circuit of the present invention
A variable matching unit connected to an antenna, a transmission / reception switching unit connected to a wireless reception unit and a wireless transmission unit, and a variable matching unit connected between the variable matching unit and the transmission / reception switching unit for transmission. A detection circuit for detecting a level of a reflected wave transmitted from the unit side, and a circuit of the variable matching circuit based on an output of the detection circuit at the time of transmission and a detection output of a level of a received wave of the wireless reception unit at the time of reception A control unit for controlling a constant.

(Operation) By performing variable control of the impedance of the variable matching circuit based on the level of the reflected wave signal of the antenna at the time of transmission and based on the level of the received signal at the time of reception, the antenna, the radio receiving unit, and the radio are automatically controlled. Match with the transmitter. The signal detected in the wireless receiver can be used as the reception signal level. By providing a switch at the input of the detection circuit, it is possible to suppress the attenuation of the received signal during reception.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Configuration of Embodiment) Next, an embodiment of the antenna matching adjustment circuit of the present invention will be described.

FIG. 1 is a diagram showing a configuration of a portable wireless device to which the antenna matching adjustment circuit of the present embodiment is applied.

The portable wireless device of the present embodiment has an antenna 1
Transmission / reception switching unit 16 for switching between wireless transmission and reception
, A radio reception unit 5, a radio transmission unit 6, and an AL that controls transmission output to make the output power of the radio transmission unit 6 constant.
A C (Auto Level Control) circuit 6 ', a control unit 9 for controlling the entire portable terminal, and a transmission level and a reception level. When the control unit 9 requests data output, data relating to the transmission level and the reception level is stored. Storage unit 8 for outputting
, A user interface 10 having an input function, a display function, etc., an external interface connector 11 for performing connection by RS232, a receiver 12, a transmitter 13, a variable matching circuit 14, a detection circuit 17 When,
The transmission output is transmitted from the transmission / reception switching unit 16 to the variable matching circuit 14, and the reception input is transmitted from the variable matching circuit 14 to the detection circuit 17.
And a circulator 1 for sending in one direction to the transmission / reception switching unit 16
5 based on the detection signal levels of the reflected wave of the transmission wave from the variable matching circuit 14 at the time of transmission and the received wave from the variable matching circuit 14 at the time of reception, which are obtained from the detection circuit 17. And a D / A converter 17 for controlling the variable matching circuit 14 so that the variable matching circuit 14 is set to an appropriate matching constant in accordance with an instruction from the control unit 9 so as to match the antenna.

FIG. 2 is a diagram showing an example of the configuration of the variable matching circuit 14. As shown in FIG. FIG. 2A shows an LC of a variable matching circuit.
A variable capacitor Ca is provided in the matching circuit, and the instruction data from the control unit 9 is converted into an analog signal by the D / A converter 17 via the choke coil Lb to control the DC potential of both electrodes of the variable capacitor Ca, thereby obtaining the capacitance value of the capacitor. Is configured to be able to be adjusted. FIG.
It is also possible to provide a variable capacitor Cd as shown in FIG. In particular, since the small antenna of a portable radio has a relatively narrow band characteristic, it is important to match the band with the transmission / reception band in a wide band system, and select a circuit constant of the control target that matches the transmission / reception band. It is preferable to configure so that

As a result, the optimum matching constant is selected at the time of transmission and at the time of reception, and communication with the best communication quality can be performed in any peripheral environment.

(Operation of Embodiment) Next, the operation of the variable matching circuit in the portable wireless device of the embodiment having the configuration shown in FIG. 1 will be described.

First, in the reception state, the transmission / reception switching circuit 16 is switched by the control unit 9 so as to output the reception signal from the circulator 15 to the radio receiver 5. The reception signal from the antenna 1 is transmitted to the radio reception unit 5 via the variable adjustment circuit 14, the circulator 15, and the transmission / reception switching unit 16.
, Is converted into an intermediate frequency wave signal, demodulated, and transmitted to the receiver 12 via the control unit 9.

Next, in the transmission state, the transmission / reception switching circuit 16 is switched by the control unit 9 so as to output the transmission signal of the radio transmitter 6 to the circulator 15. The wireless transmission unit 6 converts a signal input from the transmitter 13 via the control unit 9 into a modulated signal, and transmits the modulated signal from the antenna 1 via the transmission / reception switching unit 16, the circulator 15, and the variable matching circuit 14. Here, when the variable matching circuit 14 is in the matching state, the reflected wave signal with respect to the transmission signal is the minimum, but in the mismatched state, the reflected wave signal of a level corresponding to the degree of the mismatch is generated. The circulator function is generated from the variable matching circuit 14 toward the circulator 15 and input to the detection circuit 17. The detection circuit 17 detects the level of the reflected wave signal and outputs it to the control unit 9. The control unit 9 sets D
The control data is output to the / A converter 18 and the variable matching circuit 14 is controlled so that the reflected wave is minimized.

As described above, in the portable wireless device of the present invention, the adjustment of the variable matching adjustment circuit 14 is performed based on the reception signal level detected by the detection circuit 16 during reception.
At the time of transmission, the detection is performed based on the signal level of the reflected wave transmitted from the variable matching adjustment circuit 14 detected by the detection circuit 16.

Next, the processing operation of the adjustment control of the variable matching adjustment circuit of the embodiment of FIGS. 1 and 2A will be described with reference to FIGS. First, a control operation at the time of transmission in the control unit 9 will be described.

FIG. 3 is a diagram showing a flowchart of the operation of the mobile phone during reception.

In the portable radio shown in FIG. 1, when the receiving operation is started (110), the constant of the capacitor Ca (FIG. 2A) of the variable matching circuit 14 is set to an initial value C1 (120). The two level values (L1, L2) detected in succession and stored in the storage unit 8 are reset (210). The reception power is detected, and the reception level value (L1) at this time is stored in the storage unit 8 (220). The constant of the capacitor C1 (FIG. 2A) of the variable matching circuit 14 is represented by C1.
Is changed to [C1 + α] (230). The received power is detected and the level value (L2) is stored in the storage unit 8 (24).
0).

Check whether the receiving operation is continued (2
50). If the receiving operation has not been continued, the receiving operation is terminated (410), and this operation ends. If the receiving operation is continuously performed, the level values L1 and L2 are compared (260). If L1 ≧ L2, it is determined that the communication quality has deteriorated compared to before the change of the matching constant value, and the level values (L1, L2) stored in the storage unit 8 are reset (3).
10). If L1 <L2, it is determined that the communication quality has been improved by changing the matching constant, and the same operation as described above (210)
To (260) are repeated.

After the reset operation (310) of the storage unit 8, the reception power is detected and the level value (L1) is stored.
(320). The constant of the capacitor Ca of the variable matching circuit 14 is changed from C1 to [C1-α] (33
0). The reception power is detected, and the reception level value (L2) is stored in the storage unit 8 (340). It is confirmed whether the receiving operation is continued (350). If the receiving operation is not continued, the receiving operation is terminated (410), and this operation is terminated.

If the receiving operation is continued, the level value L1
And L2 are compared (360). If L1 ≧ L2, it is determined that the communication quality has deteriorated due to the change in the matching constant, and the operation proceeds to operation (210). If L1 <L2, it is determined that the communication quality has improved due to the change in the matching constant. 32
0) to (370) are repeated.

Next, the operation of the control unit 9 at the time of transmission by the portable wireless device will be described.

FIG. 4 is a flowchart showing the operation of the portable telephone during transmission.

In the portable radio shown in FIG. 1, when the transmission operation is started (510), the constant of the capacitor Ca (FIG. 2A) of the variable matching circuit 14 is set to an initial value C2 (520). The two transmitted reflected wave level values (L1, L2) detected in succession and stored in the storage unit 8 are reset (610). The transmitted reflected power is detected, and the level value (L1) at this time is stored in the storage unit 8 (620).
The constant of the capacitor Ca (FIG. 2A) of the variable matching circuit 14 is changed from C2 to [C2 + α] (630). The transmitted reflected power is detected, and the level value (L2) is stored in the storage unit 8 (640).

Check whether the transmission operation is continued (6)
50). If the transmission operation has not been continued, the transmission operation ends (810), and this operation ends. If the transmission operation has been performed continuously, the transmission reflection level values L1 and L2 are compared (660). If L1 ≦ L2, it is determined that the communication quality has deteriorated due to the change of the matching constant, and the storage unit 8
The transmission reflected wave level values (L1 and L2) stored in are reset again (710). If L1> L2, it is determined that the communication quality has been improved by changing the matching constant, and the above operations (610) to (660) are repeated.

After the reset operation (710) of the storage unit 8, the transmission reflected power is detected, and the level value (L1) is stored in the storage unit 8 (720). The constant of the capacitor Ca of the variable matching circuit 14 is changed from C2 to [C2-α] (730). The transmitted reflected power is detected and the level value (L2) is detected.
Is stored in the storage unit 8. It is confirmed whether or not the transmission operation is continued (750). If the transmission operation is not continued, the transmission operation is terminated (810), and this operation is terminated. If the transmission operation is continuously performed, the level values L1 and L2 are compared (760). If L1 <L2, it is determined that the communication quality has deteriorated due to the change in the matching constant, and the process proceeds to (210). If L1> L2, it is determined that the communication quality has improved due to the change in the matching constant, and the above operation (720) ) To (76)
Repeat step 0).

(Other Embodiments) Next, other embodiments of the present invention will be described in detail with reference to the drawings. FIG.
FIG. 8 is a diagram showing a second embodiment to which the antenna matching adjustment circuit of the present invention is applied. The portable wireless device according to the present embodiment has a configuration in which a high-frequency signal switch 19 is provided between the circulator 15 and the detection circuit 17.

The detection circuit 17 provided for detecting the reflected wave signal transmitted from the variable matching adjustment circuit 14 becomes a power attenuation factor in the high frequency circuit. The switch 19 has a function of eliminating the power flowing through the detection circuit 17 to prevent the reception sensitivity from deteriorating. When the portable wireless device is in a receiving state according to a control signal from the control unit 9, the switch 1
9 is turned off, and the current to the detection circuit 17 is cut off. Adjustment of the matching circuit at the time of reception is performed by using a received signal strength indicator (RSSI) output from the receiving circuit of the receiving unit 5.
ator) or the like.

As described above, in the present embodiment, the detection of the transmitted reflected wave is performed by the detection circuit 17, and the detection of the signal level of the received signal is performed by the reception circuit in the wireless reception unit 4.
As a result, it is possible to cut off the input of the detection circuit 17 when detecting the signal level of the received signal, to prevent the signal from being attenuated at the time of reception, and to improve the reception sensitivity.

FIG. 6 is a diagram showing a third embodiment to which the antenna matching adjustment circuit of the present invention is applied. This embodiment has a configuration in which the detection circuit 17 detects the levels of the received signal and the transmitted reflected wave signal in the same manner as FIG. The control unit 9 intermittently controls the circuit constant of the variable adjustment circuit 14 by performing opening / closing control of the switch 19 only at an initial time of transmission / reception switching in synchronization with a predetermined cycle or control timing of the transmission / reception switching unit 16.

The portable radio of the embodiment shown in FIGS. 5 and 6 is effective when it is difficult to improve the reception sensitivity characteristic or when the reception level is low and the control unit 9 has difficulty in recognizing it.

The processing operation of the adjustment control of the variable matching adjustment circuit can be performed in the same manner as in the first embodiment.

[0043]

According to the present invention, it is possible to optimally match the antenna at the time of transmission by selecting and transmitting the optimum matching constant based on the reflected wave transmitted from the antenna. For this reason, transmission output loss can be minimized.

Further, at the time of reception, the optimum matching constant is selected and received based on the reception level of the radio, so that the optimum antenna matching can be achieved even during reception. For this reason, it is possible to minimize the loss in the antenna at the input of the received wave.

Further, since a switch is provided at the input part of the detection circuit to suppress the attenuation of the received signal due to the insertion of the detection circuit, it is possible to prevent a decrease in reception sensitivity.

Further, according to the present invention, the matching adjustment of the antenna is performed by changing the matching constant to an appropriate one according to the frequency used, so that a narrow band antenna can be used. For this reason, it is possible to easily reduce the size and efficiency of the antenna.

[Brief description of the drawings]

[0047]

FIG. 1 is a block diagram showing a portable wireless device according to a first embodiment of the present invention.

[0048]

FIG. 2 is a block diagram showing a variable matching circuit of the present embodiment.

[0049]

FIG. 3 is a flowchart showing an operation of the mobile phone during transmission.

[0050]

FIG. 4 is a flowchart showing an operation of the mobile phone during reception.

[0051]

FIG. 5 is a block diagram showing a portable wireless device according to a second embodiment of the present invention.

[0052]

FIG. 6 is a block diagram illustrating a portable wireless device according to a third embodiment of the present invention.

[0053]

FIG. 7 is a block diagram showing a conventional portable radio device.

[0054]

[Explanation of symbols]

 Reference Signs List 1 antenna 2 antenna matching circuit (matching circuit) 3, 15 circulator 5 wireless receiving unit 6 wireless transmitting unit 6 'ALC circuit 7 monitor receiver 8 storage unit 9 control unit 10 user interface 11 external interface connector 12 receiver 13 transmitter 14 Variable matching circuit 16 Transmission / reception switching unit 17 Detection circuit 18 D / A converter 19 Switch

Claims (6)

[Claims] 1. A variable matching unit connected to an antenna,
A transmission / reception switching unit connected to the wireless reception unit and the wireless transmission unit,
Connected between the variable matching unit and the transmission / reception switching unit,
A detection circuit for detecting a level of a reflected wave transmitted from the variable matching unit at the time of transmission and a level of a received wave at the time of reception, and a control unit for controlling a circuit constant of the variable matching circuit based on an output of the detection circuit. And an antenna matching adjustment circuit. 2. The apparatus according to claim 1, wherein the detection circuit includes a switch connected through a circulator provided between the variable matching unit and the transmission / reception switching unit and intermittently connected to an input unit. Item 2. An antenna matching adjustment circuit according to Item 1. 3. A variable matching unit connected to the antenna,
A transmission / reception switching unit connected to the wireless reception unit and the wireless transmission unit,
Connected between the variable matching unit and the transmission / reception switching unit,
A detection circuit for detecting the level of the reflected wave transmitted from the variable matching unit side during transmission, and based on the output of the detection circuit during transmission and the detection output of the level of the received wave of the wireless reception unit during reception. An antenna matching adjustment circuit comprising: a control unit that controls a circuit constant of the variable matching circuit. 4. The detection circuit according to claim 1, further comprising a switch connected via a circulator provided between the variable matching unit and the transmission / reception switching unit, and connected to an input unit only during transmission. Item 3. An antenna matching adjustment circuit according to Item 3. 5. The variable matching circuit according to claim 1, wherein a constant whose frequency band is varied is selected as a circuit constant to be controlled by the variable matching circuit, and a narrow band antenna can be used in a wide band system. 3. The antenna matching adjustment circuit according to 3. 6. The antenna matching adjusting circuit according to claim 1, wherein the antenna matching adjusting circuit is applied to a portable wireless device.