Portable radio equipment

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a radio, and particularly to a portable radio in which an antenna is integrated, which can reduce the influence of an object arranged around the antenna on the antenna characteristics.

【0002】

[Conventional technology]

In recent years, mobile radios have become smaller and thinner. The condition for the portable radio is that it is easy to carry and has excellent portability. Therefore, it is very important that the portable radio is small and thin.

【0003】

On the other hand, in portable radios, the influence from the human body on transmission and reception by the antenna has become a problem. The human body causes absorption and scattering of radio waves of radio frequencies used by portable radios. Furthermore, the human body fluctuates the operating impedance of adjacent antennas. This is because the human body works as a dielectric having a very high dielectric constant of 50 or more when viewed at high frequencies. As a result, the radiation characteristics of the antenna are deteriorated by the human body.

【0004】

In addition, the smaller and thinner the radio in recent years, the closer the ear tends to be to the antenna. This proximity exacerbates the deterioration of antenna characteristics by the human body.

【0005】

When the inventors of the present invention measured the deterioration of the antenna characteristics due to the human body, the measurement results as shown in FIG. 1 were obtained. This experimental data shows the results of measuring the effect on the antenna of the human body using a portable radio with a frequency of 2 GHz as a radio model. Here, FIG. 1 shows the amount of deterioration of the gain of the antenna due to the change in the impedance of the antenna when the radio model is in a call state, with the thickness of the radio housing as a parameter. As is clear from FIG. 1, when the thickness of the terminal is thinner than 20 mm, the possibility that the ear touches the antenna increases, and when the ear touches the antenna, the gain of the antenna is greatly deteriorated.

【0006】

As mentioned earlier, the cause of this deterioration is that the impedance of the antenna fluctuates due to the influence of the human body. The human body is an object with a very high dielectric constant. When the antenna approaches such an object, the electrical length of the antenna appears to be equivalently long. In such a case, the resonance frequency of the antenna deviates from the desired value, and the impedance of the antenna changes accordingly.

【0007】

As described above, even if the impedance of the antenna is adjusted to be optimum in the portable radio unit alone, there is a problem that the impedance value deviates from the optimum value due to the proximity to the human body.

【0008】

Further, the transmission output of the portable radio may be deteriorated due to the change in the impedance of the antenna. This phenomenon will be described.

【0009】

In order to radiate radio waves from the antenna, power must first be input to the antenna. The optimum condition for the power input to the antenna is that the impedance of the feeder and the impedance of the antenna are the same value.

【0010】

When the impedance of the antenna fluctuates from the optimum value, the power transmitted through the feeder is reflected at the input end of the antenna and returned to the transmitting amplifier. Therefore, the power output from the ambu is not input to the antenna.

【0011】

The electric power reflected in this way deteriorates the performance such as the operating efficiency and the gain of the amplifier, and causes the transmission performance of the radio to be deteriorated.

【0012】

As a method for solving this, a method of examining the reflectance coefficient between the antenna and the amplifier has been conventionally proposed. In this proposal, there is a power amplification device conventionally disclosed in Document 1. In this conventional power amplification device, the current consumption value in the power amplifier is detected, the power reflected from the antenna is detected, and both detection signals are supplied to the control circuit. This control circuit sends a control signal to the variable phase device based on both detection signals to correct the phase shift generated between the antenna and the power amplifier.

【0013】

In this power amplification device, since only the phase shift is the target of correction, the range of change in the evaluation quantity is narrow, and the phase shift can be corrected by observing the evaluation quantity. However, when the deviation has two vectors, that is, the phase direction and the amplitude direction of the reflection coefficient as in the antenna of a mobile phone, there is a problem that it is difficult to correct with only the above two evaluation quantities.

【0014】

On the other hand, if the impedance of the antenna is not checked even at times other than communication, communication must be started in a state where the communication state is deteriorated at the start of communication, which causes communication interruption. This is due to the high probability that the surrounding environment will change at the start of communication in the portable radio. For example, when there is an incoming call from the standby state, the terminal in the pocket is held in the hand, set to the call state, and then pressed against the head. Here, the environment around the antenna has changed into three states in a short time.

【0015】

In the conventional method described above, depending on the system, the impedance can be checked only during communication. For example, in a CDMA system, only reception is performed during standby, and the above operation is impossible. In addition, unnecessarily radiating electromagnetic waves other than during communication is regulated by the Radio Law, which often causes problems in other systems.

【0016】

[Patent Document 1]

Japanese Patent Application Laid-Open No. 10-341117 [0017]

[Problems to be Solved by the Invention]

As described above, the conventional portable radio has a problem that the matching between the transmitter and the antenna deteriorates due to the surrounding environmental conditions, particularly the proximity to the human body, and the transmission characteristics of the antenna deteriorate.

【0018】

The present invention has been made in view of the above circumstances, and an object of the present invention is a portable radio that is not affected by an object arranged around the antenna and is capable of communication consistent with the antenna at all times. It is to provide an opportunity.

【0019】

[Means for solving problems]

According to the present invention, a power source that supplies power, a transmission circuit that is assisted by this power to generate a transmission signal, and a power detection that detects the power supplied to the transmission / reception circuit and generates a detection power signal. A circuit, an antenna having a certain antenna impedance, the transmission signal being supplied to generate a reflected signal having a certain phase according to the transmission signal, and a variable impedance, and adjusting this variable impedance. An impedance matching circuit that matches the antenna and the transmission circuit, a phase detection circuit that detects the phase of the reflected signal returned from the antenna and generates a detection phase signal, and one of the phase detection circuit and the transmission circuit. A selection circuit that is selected and connects one of the selected parts to an antenna, and the selection circuit is controlled to receive the power detection signal and the detection phase signal, and the impedance matching circuit is controlled to detect the detection phase signal and the power detection. Provided is a radio that is characterized by being composed of a control circuit that sets a variable impedance that depends on a signal.

【0020】

Further, according to the present invention, a power source for supplying power, a first transmission circuit assisted by this power to generate a first transmission signal, and a power supplied to the first transmission circuit are used. It has a power detection circuit that detects and generates a detection power signal, an antenna that has a certain antenna impedance and is supplied with the first transmission signal, and a variable impedance, and the variable impedance is adjusted to describe the above. An impedance matching circuit that matches the antenna with the first transmission circuit, and a second transmission circuit that is a phase detection circuit that generates a second transmission signal having the first phase and supplies it to the antenna. The antenna receives the second transmission signal and the second transmission signal and the reflection signal to generate the reflection signal having the second phase depending on the second transmission signal. A receiving circuit that detects a phase difference between the second phase and generates a phase difference signal and a second transmitting signal from the second transmitting circuit to the antenna are delayed and received from the antenna. A phase detection circuit including a delay line that delays the reflected signal to the circuit, and a circulator that distributes the delayed reflection signal to the receiving circuit and distributes the second transmission signal to the delay line and the receiving circuit. A selection circuit that selects one of the phase detection circuit and the transmission circuit and connects the selected one to the antenna, and controls the selection circuit to receive the power detection signal and the phase difference signal. Provided is a radio device comprising: a control circuit for controlling an impedance matching circuit to set a variable impedance depending on the phase difference signal and a power detection signal, and a control circuit for setting a variable impedance.

【0021】

Further, according to the present invention, a power source for supplying power, a transmission circuit assisted by this power to generate a transmission signal having a first phase, and a power supplied to the transmission circuit are detected. A power detection circuit that generates a detection power signal, an antenna that has a certain antenna impedance and is supplied with the transmission signal to generate a reflected signal having a second phase in response to the transmission signal, and a variable impedance. It has an impedance matching circuit that adjusts this variable impedance to match the antenna with the transmission circuit, and receives the transmission signal and the reflection signal to obtain the phase difference between the first and second phases. A receiving circuit that detects and generates a phase difference signal, a delay line that delays the transmitting signal from the transmitting circuit to the antenna, and delays the reflected signal from the antenna to the receiving circuit, and this delay. A circulator that distributes the reflected signal to the receiving circuit and distributes the transmitted signal to the delay line and the receiving circuit, and a selection circuit that selects one of the delay line and the circulator and connects the selected one to the antenna. , The selection circuit is controlled to receive the power detection signal and the phase difference signal, and the impedance matching circuit is controlled to set a variable impedance depending on the phase difference signal and the power detection signal. A radio is provided that is characterized by being made.

【0022】

Furthermore, according to the present invention, a power source for supplying current, a first transmission circuit assisted by this power to generate a first transmission signal having a first frequency, and this first transmission. It has a power detection circuit that detects the power supplied to the circuit and generates a detection power signal, an antenna having a certain antenna impedance, and an antenna to which the first transmission signal is supplied, and a variable impedance. An impedance matching circuit that adjusts the variable impedance to match the antenna with the first transmission circuit, and a phase detection circuit that generates a second transmission signal having a second frequency and a first phase. A second transmission circuit that supplies a reflected signal to the antenna, wherein the antenna generates a reflected signal having a second phase that depends on the second transmission signal, and the second transmission signal. And a receiving circuit that receives the reflected signal and detects a phase difference between the first and second phases to generate a phase difference signal, and the second transmitting circuit to the antenna. A delay line that delays the transmission signal and delays the reflected signal from the antenna to the reception circuit, and the delayed reflection signal are distributed to the reception circuit, and the second transmission signal is distributed to the delay line and the reception. A phase detection circuit including a circulator allocated to the circuit, and an output and an input to the antenna and the phase detection circuit, respectively, are allowed to pass through the second transmission signal and the reflection signal, and the first transmission of the reflection signal is allowed. A filter circuit that blocks the input to the circuit and allows the output of the first transmission signal to the antenna, and a control circuit that controls the impedance matching circuit to set a variable impedance that depends on the phase difference signal and the power detection signal. And, a radio characterized by being composed of.

【0023】

Further, according to the present invention, a current is supplied to generate a transmission signal, a transmission signal is supplied to an antenna via an impedance matching circuit, and a reflected signal returned from the antenna is detected to detect its phase. Then, the current for the transmission signal is detected, and the detected phase signal and the detected current are compared with the reference phase and the current, respectively, to determine the impedance of the impedance matching circuit, and the impedance in the impedance matching circuit connected to the antenna. An impedance adjusting method is provided, which comprises adjusting.

【0024】

BEST MODE FOR CARRYING OUT THE INVENTION

The radio device according to the embodiment of the present invention will be described below with reference to the drawings.

【0025】

FIG. 2 is a configuration diagram of a portable radio device according to an embodiment of the present invention. As shown in FIG. 1, the antenna 101 is connected to a matching circuit 102 having an adjusting function capable of adjusting the impedance of the antenna. The matching circuit 102 is connected to a changeover switch 103, one of which is connected to a reflection phase detection circuit 104 that detects the phase of the reflected signal reflected from the antenna, and the other is a transmission / reception that generates a transmission signal. It is connected to circuit 105.

【0026】

Further, the transmission / reception circuit 105 is connected to the power supply 107 via an ammeter 106 that detects the current value of the supplied power. Further, the control circuit 108 is connected to the reflection phase detection circuit 104 and the ammeter 106, and the phase signal detected by the reflection phase detection circuit 104 and the detection current signal from the ammeter 106 are input. Further, the control circuit 108 sends a control signal to the matching circuit 102 and the switch circuit 103 to control them.

【0027】

Here, the matching circuit 102 is composed of an inductance and a variable capacitance element, and the value of the impedance of the antenna 101 can be changed by changing the variable capacitance element by a control signal from the control circuit 108.

【0028】

The reflection phase detection circuit 104 measures how much the phase of the signal transmitted from the transmission circuit (not shown) inside the reflection phase detection circuit 104 is changed by the antenna 101 by receiving the reflection signal. As already described, the reflected signal from the terminal of the antenna 101 is changed by the surrounding environment of the antenna 101. This change in the reflected signal occurs based on the change in the input impedance of the antenna as described in the prior art, and can be regarded as an equalized change in impedance. Therefore, if the correlation between the state in which the antenna 101 is placed and the reflection phase Sp is investigated in advance, it is possible to infer the state in which the antenna is placed from the value of the reflection phase Sp from the antenna 101. .. Further, from the measured reflection phase Sp, the adjustment of the matching circuit 102 can be determined in order to return the reflection phase Sp to the reference state. That is, the impedance of the antenna 101 can be estimated by detecting the reflected signal from the antenna 101. If the value of the variable capacitance element of the matching circuit 102 is changed based on the impedance of the antenna 101, the transmission power can be optimally maintained.

【0029】

Power is supplied to the transmission / reception circuit 105 from the power supply circuit 107, and this supply power is modulated based on digital information signals (for example, voice and image signals) sent from an information signal generator (not shown), and the transmission frequency is also transmitted. The transmission signal is generated and transmitted from the antenna 101. The antenna 101 transmits a transmission signal into the air, and a part of the transmission signal is returned to the transmission / reception circuit 105 side as a reflected wave. The amount of reflection of this reflected signal is changed by the value of the impedance of the antenna 101.

【0030】

The impedance of the antenna 101 is changed by the environment around the antenna 101, and the reflected signal sent back is also changed. This reflected signal changes the gain and efficiency of the transmit amplifier in the transmit / receive circuit 105. Therefore, the fluctuation of the reflected signal causes the fluctuation of the current consumption of the transmission / reception circuit 105. This fluctuation in current consumption is measured by the ammeter 106, and the current level SI is sent to the control circuit 108. The value of this current level SI has a strong correlation with the situation in which the antenna is placed. Therefore, this current level SI can be used as an evaluation function for adjusting the matching circuit.

【0031】

The received signal received by the antenna 101 is supplied to the transmission / reception circuit 105 through the matching circuit 102 and the changeover switch 103. Since processing in a normal wireless terminal or base station is applied to the processing of the received signal, the description of the processing of the received signal will be omitted.

【0032】

Next, the operation of the control circuit 108 will be described with reference to the flowchart shown in FIG.

【0033】

First, the movable contact of the switch 102 is connected to the first fixed contact Sa by the control signal from the control circuit 108, and the phase detection mode for detecting the phase of the reflected signal is set (step S1). Next, a phase detection signal is sent to the control circuit 108 from a transmission circuit (not shown) in the phase detection circuit 104, and the phase Sp of the reflected signal from the antenna 101 is detected (step S2).

【0034】

Next, the movable contact of the switch 102 is connected to the second fixed contact Sb, and the current detection mode for detecting the transmission current is set (step S3). Therefore, the transmission power is supplied to the transmission / reception circuit 105, the transmission signal is supplied from the transmission / reception circuit 105 to the antenna 101, and the current level SI of the power supplied to the transmission / reception circuit 105 is detected by the ammeter 106 (step S4). The phase Sp and current level SI of this reflected signal are given to the control circuit 108, and the phase Sp and current level SI are compared with the predetermined reference values Sp0 and SI0 (step S5). The reference values Sp0 and SI0 are measured in advance in a state where no other object is close to the antenna 101, and are stored in the storage circuit in the measurement.

【0035】

When the phase Sp and the current level SI deviate from the predetermined reference values Sp0 and SI0, the matching circuit 102 is adjusted. (Step S6) After this adjustment, the phase Sp and the current value SI of the reflected signal are measured in the same manner, and the evaluation is repeated. The same adjustment and measurement are repeated until the detected phase Sp and the detected current level SI reach the predetermined reference values Sp0 and SI0, and when the phase Sp and the current level SI reach the predetermined reference values Sp0 and SI0. , Communication using the transmission / reception circuit 105 is started in the transmission / reception mode (step S7).

【0036】

In this way, since the communication is started after the impedance of the antenna is set to the optimum state, the influence of the surroundings where the wireless terminal is used is reduced, and the communication can be started in the optimum state.

【0037】

Next, another control method in the circuit shown in FIG. 2 will be described with reference to the flowchart shown in FIG.

【0038】

First, the movable contact of the switch 102 is connected to the fixed contact Sa by the control signal from the control circuit 108, and the phase detection mode for detecting the phase of the reflected signal is set (step S11). Next, a transmission signal from a transmission circuit (not shown) in the phase detection circuit 110 is transmitted, a reflected signal from the antenna 101 is detected, and the phase Sp of the reflected signal is detected (step S12).

【0039】

Next, a method of adjusting the matching circuit 102 based on the value of the detected phase Sp is determined (step S13). In this step 13, when the current level Sp is compared with the reference value Sp0, the method of adjusting the capacitance element of the matching circuit according to the phase amount Sp, that is, whether to increase or decrease the capacitance is determined. When the phase Sp deviation of the reflected signal is large depending on the design of the amplifier that constitutes the transmission / reception circuit, the capacitance of the capacitive element of the matching circuit is increased to approach the reference value, or the capacitive element of the matching circuit The capacity may be reduced to approach the reference value, and the method is determined.

【0040】

When the policy of the adjustment method is determined, the movable contact of the switch 103 is connected to the second fixed contact Sb, and the phase detection mode for detecting the phase of the reflected signal is set (step S14). Next, the ammeter 106 detects the current level SI (step S15). Then, the current level SI is compared with the reference value SI0 (step S16). As described above, this reference value SI0 is measured and stored in advance in a state where no other object is in close proximity to the antenna 101.

【0041】

If the current level SI deviates from the reference value SI0, the matching circuit 102 is adjusted (step S17), and the measurement and evaluation of the current value SI are repeated. It is repeated until the current level SI reaches the reference value SIO, and when the current level SI reaches the reference value, the communication in the transmission / reception circuit 105 is started in the transmission / reception mode (step S18).

【0042】

Therefore, in such control, only the current value SI is used as the evaluation function to adjust the matching circuit 102. Therefore, the time used for adjustment can be reduced.

【0043】

As described above, in this embodiment, the communication performance of the radio when a human body or other object is close to the antenna can be improved.

【0044】

FIG. 5 shows a specific circuit configuration of the phase detection circuit 104 of the portable radio shown in FIG. In FIG. 5, the circuit is the same as that shown in FIG. 2 except for the phase detection circuit 104, and the description thereof will be omitted.

【0045】

As shown in FIG. 5, the phase detection circuit 104 includes a transmission circuit 104-1 that sends a signal for measuring the phase of the reflected signal and a reception circuit 104-that receives the reflected signal as a reflected wave reflected from the antenna 101. 2 is provided. The transmission circuit 104-1 and the reception circuit 104-2 are connected to the circulator 104-3. Further, the circulator 104-3 is connected to the switch 103 via the delay line 104-4.

【0046】

The transmission circuit 104-1 and the reception circuit 104-2 include a circuit for phase modulation and demodulation. The circulator 104-3 sends the transmission signal S1 from the transmission circuit 104-1 to the reception circuit 104-2, and also sends the transmission signal generated from the transmission circuit 104-1 via the delay line 104-4 to the antenna 101. It feeds and supplies the reflected signal reflected from the antenna 101 via the delay line 104-4 to the receiving circuit 104-2. That is, the circulator 104-3 selectively supplies the transmission signal from the transmission circuit 104-1 and the reflected signal from the antenna 101 to the reception circuit 104-2. Further, the delay line 104-4 uses an element such as a surface acoustic wave filter to give a delay of a relatively long time to the transmitted signal toward the antenna 101 and the reflected signal from the antenna.

【0047】

The receiving circuit 104-2 has a circuit configuration as shown in FIG. 6 as an example. The receiving circuit 104-2 includes a demodulation circuit 104-2A that detects and demodulates the transmission signal or the reflected signal from the circulator 104-3, and the phase of the transmission signal or the reflected signal demodulated by the demodulation circuit 104-2A. Is stored as phase information in the storage circuit 104-2B. The stored phase information of the transmission demodulation signal and the phase information of the reflection demodulation signal are given to the comparison circuit 104-2C, and the phase difference between the two is detected. The detected phase difference signal is supplied to the control circuit 108.

【0048】

Next, the operation of the receiving circuit 104 and the control circuit 108 having the phase detection function shown in FIGS. 5 and 6 will be described with reference to the flowchart shown in FIG. 7. The first step is phase detection in the free space state of antenna 101 to determine the phase reference value. The following operations are performed when there are no objects in the vicinity of the antenna.

【0049】

First, the movable contact of the switch 102 is connected to the fixed contact Sa by the control signal Ss from the control circuit 108, and the phase detection mode for detecting the phase of the reflected signal is set (step S21). Next, a transmission signal is transmitted from the transmission circuit 104-1. At this time, the signal is unmodulated and the pulse width is set to be less than half of the delay time of the delay line 104-4.

【0050】

The circulator 104-3 is adjusted in advance so that a part of the transmitted signals S1 is sent directly to the receiving circuit 104-2 and the remaining transmitted signal S2 is sent to the delay line 104-4. The receiving circuit 104-2 detects and demodulates the transmission signal S1, collects the phase information P1, and starts measuring the time from the start of receiving the transmission signal S1 (step S23).

【0051】

The transmission signal S2 sent to the delay line 104-4 is sent to the antenna 101 via the delay line 104-4, the switch 103, and the matching circuit 102. Then, in this antenna 101, the transmission signal is reflected according to the difference in impedance between the matching circuit 102 and the antenna 101. This reflected signal S2 is returned to the circulator 104-3 via the matching circuit 102, the switch 103, and the delay line 104-4, and is input to the receiving circuit 104-2 by the circulator 104-3. Similarly, the receiving circuit 104-2 detects and demodulates the reflected signal S2, thereby acquiring the phase information P2 of the reflected signal S2 (step S24).

【0052】

At this time, in order to confirm that it is the reflected signal S2, the time measured from the time when the transmission signal S1 is received is used. That is, the round-trip delay time given by the delay line 104-4 is measured in advance, and the input signal received after that time is determined to be the reflected signal S2 reflected from the antenna. Here, since the signal S2 is delayed by the delay line 104-4, interference does not occur between the reflected signal S2 and the transmitted signal S1.

【0053】

In the comparison circuit 104-2C, the phase information P1 of the transmission signal S1 and the phase information P2 of the reflection signal S2 are compared, and the phase difference information P is given to the control circuit 108. In the control circuit 108, the phase difference P representing the state of the free space of the antenna is stored in the memory thereof as a reference (step S25). The reference is determined as described above. Next, the measurement sequence in the actual state will be described. First is the phase measurement, which is measured in the same way as the reference was measured. Therefore, since it is the same up to S25, the description is omitted. The control circuit compares the measured phase with the reference (step S26).

【0054】

Next, the policy of the adjustment method of the matching circuit 102 is determined from the compared phase values (step S27). As described above, this adjustment policy determines how to adjust the capacitance element of the matching circuit, that is, whether to increase or decrease the capacitance, according to the phase of the reflected signal in comparison with the reference value of the current value. is there. Depending on the design of the amplifier that composes the transmitter / receiver circuit, when the phase shift of the reflected wave is large, the capacitance of the capacitive element of the matching circuit may be increased to approach the reference value, or the capacitance of the capacitive element of the matching circuit may be reduced. It may approach the standard value, and the method is determined.

【0055】

When the policy is decided, the movable contact of the switch 103 is connected to the fixed contact Sb, and the current detection mode for detecting the transmission current is set (step S28). The ammeter 106 then detects the current level SI (step S29). Then, the current level SI is compared with the reference value SI0 (step S30). As described above, this reference value SI0 is measured in advance in a state where no other object is in close proximity to the antenna 101.

【0056】

If the current level SI deviates from the reference value SI0, the matching circuit 102 is adjusted by Sm (step S31), and the measurement and evaluation of the current value SI are repeated. It is repeated until the current level SI reaches the reference value SIO, and when the current level SI reaches the reference value, communication using the transmission / reception circuit 105 in the transmission / reception mode is started (step S32).

【0057】

In this way, the communication performance of the radio can be improved when the human body or other object is in close proximity to the antenna.

【0058】

The frequencies used by the phase detection circuit 108 and the transmission / reception circuit 105 do not have to be exactly the same. The effect of the invention can be obtained if the frequencies are relatively similar.

【0059】

Further, if the frequency used in the reflection phase detection circuit 108 is the frequency of the IMS band (2.4 GHz), it is advantageous because the signal leaked from the antenna 101 does not adversely affect other radios.

【0060】

FIG. 8 shows a circuit of a mobile terminal according to another embodiment of the present invention, and the transmission unit 104-1 constituting the phase detection circuit 104 shown in FIG. 5 is shared by the transmission / reception circuit 105. That is, when the impedance of the antenna 101 is adjusted, the transmitted signal from the transmission / reception circuit 105 is used to detect the reflected wave from the antenna.

【0061】

According to such a circuit configuration, the portable radio can be miniaturized.

【0062】

FIG. 9 shows a circuit of a mobile terminal according to still another embodiment of the present invention. In the circuit shown in FIG. 9, in the portable radio shown in FIG. 2, a common device 110 is used instead of the switch 102. The commoner 110 is composed of, for example, a filter, and the frequency F1 of the transmission signal SF1 generated from the phase detection circuit 104 and the frequency F2 of the transmission signal SF2 generated from the transmission / reception circuit 105 are different from each other. Will have a function like the switch 102. That is, since the reflected wave generated from the phase detection circuit 104 and reflected from the antenna has the frequency F1, it is supplied to the phase detection circuit 104 via the duplexer 110 and generated from the transmission / reception circuit 105. Since the reflected wave reflected from the antenna has a frequency F2, it is prevented from being supplied to the phase detection circuit 104 via the duplexer 110. Here, if, for example, a radio whose ISM band (2.4 GHz band) is generated from the phase detection circuit 104 is used as the operating frequency F1, the state of the antenna of the radio without adversely affecting other radios. It becomes possible to adjust the matching circuit 102.

【0063】

Further, FIG. 10 shows a circuit configuration of a portable radio according to another embodiment of the present invention. In FIG. 10, a second antenna 101-2 is provided in addition to the first antenna 101, and the second antenna 101 replaces the matching circuit 102 arranged between the first antenna 101 and the switch 103. A matching circuit 102 is placed between -2 and ground. The second antenna 101-2 is called a non-feeding element, and the second antenna 101-2 is electromagnetically coupled to the first antenna 101 by controlling the impedance of the matching circuit 102. If the first antenna 101 and the second antenna 101-2 are combined, the characteristics of the second antenna 101-2 are changed. Therefore, even if the antenna 101 shown in FIG. 10 approaches the human body and its antenna characteristics change, the control circuit 108 controls the matching circuit 102 and its impedance is changed as described in other examples. For example, communication is realized with appropriate antenna characteristics. The matching circuit 102 may be located at the base of the second antenna 101-2 or between the tip of the antenna 101-2 and the ground. In this method, since the matching circuit 102 is not inserted between the antenna 101 and the transmission / reception circuit 105, there is an advantage that the gain is not deteriorated due to the loss of the matching circuit 102.

【0064】

Although the above-described embodiment describes the mobile terminal, it is clear that the present invention can be applied not only to the mobile terminal but also to various radios having an antenna, for example, a base station.

【0065】

Further, in the above-described embodiment, a single matching circuit in which a capacitor element whose capacitance value changes by applying a bias voltage such as a varicap diode and an inductance is adopted. However, the circuit of the radio may include a plurality of matching circuits, each having a fixed capacitor element and inductance, and a high frequency switch that switches the matching circuit under the control of the control circuit. With such a circuit configuration, the same effect as when the matching circuit is controlled can be obtained.

【0066】

Further, in the above-described embodiment, the ammeter 106 is used to evaluate the power supplied to the transmission / reception circuit 105 driven by a substantially constant and relatively low voltage. If the transmit / receive circuit 105 is driven by a variable voltage instead of this substantially constant and relatively low voltage, then an ammeter must be used or the current supplied to the transmit / receive circuit 105. It is required that power is calculated from voltage and current using not only an ammeter to measure but also a voltmeter to measure the voltage applied to the transmission / reception circuit 105.

【0067】

[Effect of the invention]

As described above, according to the present invention, there is provided a portable radio that is not affected by an object arranged around the antenna and is capable of communication consistent with the antenna at all times.

[Simple explanation of drawings]

[Figure 1]

It is a graph which shows the relationship between the thickness of a portable radio and the antenna mismatch loss.

[Figure 2]

It is a block diagram which shows schematic the circuit of the portable radio which concerns on one Embodiment of this invention.

[Fig. 3]

It is a flowchart which shows the operation of the portable radio shown in FIG.

[Fig. 4]

It is another flowchart which shows the operation of the portable radio shown in FIG.

[Fig. 5]

It is a block diagram which shows schematic the circuit of the portable radio which concerns on other embodiment of this invention.

[Fig. 6]

It is a block diagram which shows the circuit example of the receiving circuit shown in FIG. 5 schematicly.

[Fig. 7]

It is a flowchart which shows the operation of the portable radio shown in FIG. 5 and FIG.

[Fig. 8]

It is a block diagram which shows schematic the circuit of the portable radio which concerns on still another Example of this invention.

[Fig. 9]

It is a block diagram which shows schematic the circuit of the portable radio which concerns on still another Example of this invention.

[Fig. 10]

It is a block diagram which shows schematic circuit of the portable radio which concerns on still another Example of this invention.

[Explanation of symbols]

101 ... antenna 102 ... Matching circuit 103 ... Changeover switch 102 ... switch 104 ... Reflection phase detection circuit 104-1 ... Transmission circuit 104-2 ... Receive circuit 104-3 ... Circulator 104-4 ... Delay line 105 ... Transmission / reception circuit 106 ... ammeter 107 ... Power circuit 108 ... Control circuit 110 ... commoner