JP2012039658A - Mobile terminal and antenna control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile terminal and antenna control method, capable of suppressing degradation of send/receive performance by detecting a characteristic change in an antenna changing depending on a usage state and adapting to the changing antenna characteristic.SOLUTION: A mobile terminal 10 includes a reception level measurement part 113 that measures reception levels of high-frequency signals at a reference frequency with a resonance frequency of an antenna as a reference and at an offset frequency from the reference frequency by a predetermined frequency, and an antenna control part 115 that shifts a resonance frequency in the direction of the reference frequency by controlling the antenna 13 when the reception level at the offset frequency measured by the reception level measurement part 113 is higher than the reception level at the reference frequency.

Description

  The present invention relates to a mobile terminal including an antenna, a high frequency amplifier circuit, and an impedance matching circuit, and an antenna control method for the mobile terminal.

  Conventionally, in a mobile terminal such as a mobile phone terminal, when the characteristic impedance of the antenna changes depending on the usage state, the radio signal transmission / reception performance is greatly affected.

  There is known a method for detecting deterioration of transmission / reception performance due to such a change in characteristic impedance of an antenna. For example, the wireless communication device (wireless base station) causes the mismatch between the characteristic impedance of the antenna and the impedance of the power feeding side (high frequency amplifier circuit) based on the fluctuation in the level of the detection signal, specifically, the antenna connection A method for detecting an abnormality in an antenna such as disconnection or breakage of a terminal has been proposed (see Patent Document 1).

Japanese Patent No. 3462391 (page 4-5, Fig. 1)

  By the way, in the case of a mobile terminal, there is a problem that the characteristic impedance of the antenna changes depending on the usage state of the mobile terminal, not limited to the abnormality of the antenna.

  For example, the characteristic impedance of the antenna changes between when a human is near the mobile terminal and when a metal object is present. Further, in the folding mobile terminal, the characteristic impedance of the antenna changes between the folded state and the unfolded state.

  Further, when the characteristic impedance of the antenna changes, the resonance frequency of the antenna, that is, the center frequency of the radio signal received via the antenna also changes.

  That is, in the conventional method described above, the antenna abnormality is simply detected based on the level fluctuation of the detection signal. For this reason, there has been a problem that it is impossible to detect characteristic changes such as the characteristic impedance and resonance frequency of the antenna that change depending on the usage state of the mobile terminal, and to adapt to the changed characteristic impedance and resonance frequency.

  The present invention has been made in view of such a situation, and is capable of detecting a change in antenna characteristics that changes according to the use state and adapting to the changing antenna characteristics to suppress deterioration in transmission and reception performance. An object is to provide a terminal and an antenna control method.

In order to solve the problems described above, the present invention has the following features. First, the first feature of the present invention is that an antenna (antenna 13), a high-frequency amplifier circuit (high-frequency amplifier circuit 107) that amplifies a high-frequency signal output from the antenna, and an impedance (impedance Z ₁ ) of the antenna A mobile terminal (mobile terminal 10) comprising a matching circuit (matching circuit 103) for matching the impedance (impedance Z ₂ ) of the high-frequency amplifier circuit, wherein the first terminal (terminal 105 ₁ ) and the first terminal It has a second terminal (terminal 105 ₂ ) located in the rear stage and a third terminal (terminal 105 ₃ ) located in the rear stage of the second terminal, and only in one direction from the first terminal to the second terminal. And a circulator (circulator 105) for passing the high-frequency signal only in one direction from the second terminal to the third terminal, A detector (detector 109) for detecting the presence / absence of a high-frequency signal, and a matching circuit control unit that changes the impedance of the antenna by controlling the matching circuit when the high-frequency signal is detected by the detector ( The matching circuit is connected to the first terminal, the high-frequency amplifier circuit is connected to the second terminal, and the detector is connected to the third terminal. This is the gist.

  According to such a mobile terminal, when the impedance of the antenna and the impedance of the high-frequency amplifier circuit do not match, the reflected wave from the high-frequency amplifier circuit is output as a high-frequency signal to the third terminal of the circulator. That is, it is possible to detect that the characteristic impedance of the antenna has changed according to the usage state of the mobile terminal. Furthermore, when it is detected that the characteristic impedance of the antenna has changed, the impedance of the antenna can be changed by controlling the matching circuit.

  That is, according to such a mobile terminal, it is possible to suppress deterioration in transmission / reception performance by detecting changes in antenna characteristics that change according to usage conditions and adapting to changes in antenna characteristics.

  A second feature of the present invention relates to the first feature of the present invention, wherein the matching circuit control unit increases the impedance of the antenna when the high-frequency signal is detected by the detector. To do.

  A third feature of the present invention is an antenna control method in a mobile terminal comprising an antenna and a high-frequency amplifier circuit that amplifies a high-frequency signal output from the antenna, the impedance of the antenna and the impedance of the high-frequency amplifier circuit And the step of detecting the presence or absence of a reflected wave from the high-frequency amplifier circuit that is generated in accordance with the mismatch, and the step of changing the impedance of the antenna when the reflected wave is detected. .

The fourth feature of the present invention is that an antenna (antenna 13), a high-frequency amplifier circuit (high-frequency amplifier circuit 107) that amplifies a high-frequency signal output from the antenna, and the antenna is connected to the impedance (impedance). Z ₁ ) and a mobile terminal (mobile terminal 10) including a matching circuit (matching circuit 103) for matching the impedance (impedance Z ₂ ) of the high-frequency amplifier circuit, wherein the reference is based on the resonance frequency of the antenna A measurement unit (reception level measurement unit 113) that measures a reception level (for example, RSCP) of the high-frequency signal at a frequency (frequency f ₀ ) and an offset frequency (frequency f ₁ , frequency f ₂ ) that is a predetermined frequency away from the reference frequency. ) And the offset frequency measured by the measurement unit An antenna control unit (antenna control unit 115) that shifts the resonance frequency in the direction of the reference frequency by controlling the antenna when the reception level in number is higher than the reception level at the reference frequency; The gist is to provide.

  According to such a mobile terminal, the measurement unit measures the reception level of the high-frequency signal at the reference frequency based on the resonance frequency of the antenna and the offset frequency that is a predetermined frequency away from the reference frequency.

  For this reason, it is possible to detect a change in the resonance frequency of the antenna accompanying a change in the characteristic impedance of the antenna in accordance with the usage state of the mobile terminal. When the reception level of the high frequency signal at the offset frequency is higher than the reception level at the reference frequency, the resonance frequency is shifted in the direction of the reference frequency by controlling the antenna.

  That is, according to such a mobile terminal, it is possible to suppress deterioration in transmission / reception performance by detecting changes in antenna characteristics that change according to usage conditions and adapting to changes in antenna characteristics.

A fifth feature of the present invention relates to the fourth feature of the present invention, wherein the measurement unit has a higher offset frequency (frequency f ₂ ) higher than the reference frequency as the offset frequency, and higher than the reference frequency. The reception level at a low low offset frequency (frequency f ₁ ) is measured, and the antenna control unit shifts the resonance frequency in the direction of the reference frequency based on the reception level at the high offset frequency and the low offset frequency. The gist is to make it.

According to a sixth aspect of the present invention, there is provided an antenna control method in a mobile terminal including an antenna, the reference frequency being based on a resonance frequency of the antenna, and the high-frequency signal at an offset frequency separated from the reference frequency by a predetermined frequency. Measuring the reception level, and if the reception level at the measured offset frequency is higher than the reception level at the reference frequency, the resonance frequency is adjusted in the direction of the reference frequency by controlling the antenna. And a step of shifting.

  According to the features of the present invention, there is provided a mobile terminal and an antenna control method capable of suppressing deterioration in transmission / reception performance by detecting changes in antenna characteristics that change according to usage conditions and adapting to the changing antenna characteristics. Can do.

1 is an overall schematic configuration diagram of a mobile terminal 10 according to an embodiment of the present invention. It is a functional block block diagram of the radio | wireless communication part 100 which concerns on 1st Embodiment of this invention. Wireless communication unit 100 according to the first embodiment of the present invention is a diagram showing an operation flow for controlling the impedance Z ₁ of the antenna 13 _{(characteristic} impedance). It is a functional block block diagram of 100 A of radio | wireless communication parts which concern on 2nd Embodiment of this invention. It is a figure which shows the operation | movement flow in which 100 A of radio | wireless communication parts which concern on 2nd Embodiment of this invention control the resonant frequency of the antenna. It is a figure which shows an example of the reference frequency and offset frequency which concern on 2nd Embodiment of this invention.

  Next, an embodiment of the present invention will be described. Specifically, (1) the first embodiment, (2) the second embodiment, and (3) other embodiments will be described.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(1) 1st Embodiment In 1st Embodiment, the mobile terminal which detects the change of the characteristic impedance of an antenna using a circulator and a detector is demonstrated. Specifically, (1.1) Schematic configuration of mobile terminal, (1.2) Functional block configuration of radio communication unit, (1.3) Operation of radio communication unit, and (1.4) Actions / effects will be described. To do.

(1.1) Schematic configuration of mobile terminal FIG. 1 is an overall schematic configuration diagram of a mobile terminal 10 according to the present embodiment. As shown in FIG. 1, the mobile terminal 10 includes a main body unit 11, a liquid crystal display unit 12, and an antenna 13.

  The main body part 11 and the liquid crystal display part 12 are connected so as to be rotatable. That is, the mobile terminal 10 can be folded or expanded around the connection part.

  In addition, a radio communication unit 100 that performs radio communication with a radio base station (not shown) is provided inside the main body unit 11.

(1.2) Functional Block Configuration of Radio Communication Unit FIG. 2 is a functional block configuration diagram of the radio communication unit 100 provided inside the mobile terminal 10 (main body unit 11). As shown in FIG. 2, the wireless communication unit 100 includes a duplexer 101, a matching circuit 103, a circulator 105, a high frequency amplifier circuit 107, a detector 109, and a matching circuit control unit 111.

  An antenna 13 is connected to the duplexer 101. The duplexer 101 separates an uplink signal transmitted toward the radio base station and a downlink signal transmitted from the radio base station. A downlink signal received via the antenna 13 is output to the matching circuit 103.

Matching circuit 103, an impedance _{Z 1} of the antenna 13, matching an impedance _{Z 2} of the high-frequency amplifier circuit 107 (matching) make.

In particular, in the present embodiment, when the impedance Z ₁ (characteristic impedance) of the antenna 13 changes depending on the usage state of the mobile terminal 10, the matching circuit 103 determines the impedance of the antenna 13 based on the control from the matching circuit control unit 111. to change the Z _1. Examples of the case where the characteristic impedance of the antenna 13 changes depending on the usage state of the mobile terminal 10 include a case where a person is present near the mobile terminal 10 and a case where a metal object is present. Further, the characteristic impedance of the antenna 13 changes even when the mobile terminal 10 is expanded from the folded state.

The circulator 105 is connected to the matching circuit 103, the high frequency amplifier circuit 107, and the detector 109. Specifically, the circulator 105 includes a terminal 105 ₁ (first terminal), a terminal 105 ₂ (second terminal), and a terminal 105 ₃ (third terminal). Terminal 105 ₂ is positioned downstream of the terminal 105 _1. Terminal 105 ₃ is positioned downstream of the terminal 105 _2.

Matching circuit 103 is connected to a terminal 105 _1. High-frequency amplifier circuit 107 is connected to a terminal 105 _2. Further, detector 109 is connected to the terminal 105 _3.

The circulator 105 in the direction from the terminal 105 ₁ to the terminal 105 ₂ only, to pass the high-frequency signal output from the antenna 13 side. Further, the circulator 105, only in the direction from the terminal 105 ₂ to the terminal 105 ₃ is passed through the high-frequency signal.

  The high frequency amplifier circuit 107 amplifies the high frequency signal output from the antenna 13. Specifically, the high frequency signal output from the antenna 13 is input to the high frequency amplifier circuit 107 via the duplexer 101, the matching circuit 103, and the circulator 105.

Detector 109 detects the presence or absence of the high frequency signal output to the terminal 105 ₃ of the circulator 105. Specifically, detector 109 detects the current output to the terminal 105 ₃ of the circulator 105.

  When detecting the high-frequency signal, the detector 109 outputs to the matching circuit control unit 111 that the high-frequency signal has been detected.

In the wireless communication unit 100 having the configuration described above, the impedance Z ₁ of the antenna 13 (and duplexer 101), if the impedance Z ₂ of the high-frequency amplifier circuit 107 are mismatched, one high-frequency signal output from the antenna 13 The part is not input to the high-frequency amplifier circuit 107 and returns to the antenna 13 as a reflected wave from the high-frequency amplifier circuit 107. That is, the reflected waves from the high-frequency amplifier circuit 107 is generated with the mismatch between the impedance Z ₁ and the impedance Z _2.

On the other hand, if the matching circuit 103 is operating optimally, that is, when the impedance Z ₁ and the impedance Z ₂ are matched, reflected waves from the high-frequency amplifier circuit 107 does not occur. In this case, detector 109, a high-frequency signal at terminal 105 _3, specifically, does not detect the reflected waves from the high-frequency amplifier circuit 107. Further, the reflected wave from the high-frequency amplifier circuit 107, by the function of the circulator 105 is outputted only in the direction from the terminal 105 ₂ to the terminal 105 _3.

The matching circuit control unit 111 controls the matching circuit 103. Specifically, the matching circuit control unit 111, if the high-frequency signal (reflected wave) is detected, changing the impedance Z ₁ of the antenna 13 by controlling a matching circuit 103 by the detector 109. In the present embodiment, the matching circuit control unit 111 increases the impedance Z _{1 of the} antenna 13 when a high frequency signal is detected by the detector 109.

Here, if the high-frequency signal by the detector 109 (reflected wave) is detected, the impedance Z ₁ of the antenna 13, is less whether than the impedance Z ₂ of the high-frequency amplifier circuit 107, can not be determined. In the present embodiment, the matching circuit control unit 111, if the high-frequency signal (reflected wave) is detected, the impedance Z ₁ is smaller assuming increasing the impedance Z ₁ than the impedance Z ₂ by detector 109. The specific method of controlling the impedance Z ₁ of the antenna 13 will be described later.

(1.3) Operation of Radio Communication Unit Next, the operation of the mobile terminal 10 will be described. Specifically, an operation in which the wireless communication unit 100 controls the impedance Z ₁ (characteristic impedance) of the antenna 13 will be described.

FIG. 3 shows an operation flow in which the wireless communication unit 100 controls the impedance Z ₁ (characteristic impedance) of the antenna 13. As shown in FIG. 3, in step S10, the radio communication unit 100 determines the terminal 105 ₃ of the circulator 105, whether it has detected a radio frequency signal (reflected wave). Specifically, the radio communication unit 100 determines whether there is a detected current _{I 0} at terminal 105 _3.

If the detected current I ₀ is present (YES in step S10), the wireless communication unit 100 increases the impedance Z ₁ (characteristic impedance) of the antenna 13 in step S20. Specifically, by controlling the matching circuit 103, predefined value impedance Z ₁ of the antenna 13 (e.g., 1 [Omega minute) increases.

In step S30, the radio communication unit 100 determines whether there is a detected current _{I 1} at terminal 105 _3.

When there is the detection current I ₁ (YES in step S30), in step S40, the wireless communication unit 100 determines whether or not the detection current I ₁ is equal to or less than the detection current I ₀ .

If the detected current _{I 1} is equal to or less than the detection current _{I 0} (YES in step S40), in step S50, the radio communication unit 100 has been pre-defined impedance _{Z 1} of the antenna 13 by controlling the matching circuit 103 the value Increase.

In step S60, the radio communication unit 100 determines whether there is a detected current _{I 2} at terminal 105 _3.

If there is a detected current _{I 2} (YES in step S60), in step S70, the wireless communication unit 100, the wireless communication unit 100, the detection current _{I 2} determines whether the detected current _{I 1} below.

On the other hand, when there is no detection current I ₀ , detection current I ₁ or detection current I ₂ (NO in step S 10, NO in step S 30 or NO in step S 60), the wireless communication unit 100 is connected to the antenna 13 (and the duplexer 101). It determines the impedance _{Z 1,} and the impedance _{Z 2} of the high-frequency amplifier circuit 107 is matched.

If the detected current _{I 2} is the detected current _{I 1} or less (YES in step S70), in step S80, the radio communication unit 100 has been pre-defined impedance _{Z 1} of the antenna 13 by controlling the matching circuit 103 the value Increase.

If the detected current _{I 2} exceeds the detection current _{I 1} (NO in step S70), in step S90, the radio communication unit 100, predefined value decreases the impedance _{Z 1} of the antenna 13 by controlling a matching circuit 103 Let

Further, if the detected current _{I 1} exceeds the detection current _{I 0} (NO in step S40), in step S100, the radio communication unit 100, defined impedance _{Z 1} of the antenna 13 in advance by controlling the matching circuit 103 Decrease the value.

Next, in steps S110 to S140, processing similar to that in steps S60 to S90 described above is executed. The wireless communication unit 100, the current at terminal 105 _3, that is, until the reflected wave is not detected, and repeats the processing in step S40～S140.

(1.4) Operation and Effect mobile terminals 10, specifically, according to the wireless communication unit 100, when the impedance _{Z 2} of the impedance _{Z 1} and the high-frequency amplifier circuit 107 of the antenna 13 is not matched, the high frequency amplifier reflected wave from the circuit 107 is output as a high-frequency signal to the terminal 105 ₃ of the circulator 105. That is, it is possible to detect that the characteristic impedance of the antenna 13 has changed according to the usage state of the mobile terminal 10. Furthermore, when it is detected that the characteristic impedance of the antenna 13 has changed, the impedance Z _{1 of the} antenna 13 can be changed by controlling the matching circuit 103.

  That is, according to the wireless communication unit 100, it is possible to suppress the deterioration of the transmission / reception performance of the wireless communication unit 100 by detecting the characteristic change of the antenna 13 that changes according to the use state and adapting to the changing characteristic of the antenna 13. .

In the present embodiment, when the high-frequency signal (reflected wave) is detected by the detector 109, the matching circuit control unit 111 increases the impedance Z ₁ of the antenna 13. As described above, when a high-frequency signal is detected by the detector 109, it cannot be determined whether or not the impedance Z _{1 of the} antenna 13 is smaller than the impedance Z ₂ of the high-frequency amplifier circuit 107.

Therefore, in the present embodiment, the matching circuit control unit 111, the case where the high-frequency signal is detected, the impedance Z ₁ is smaller assuming increasing the impedance Z ₁ than the impedance Z _2. Furthermore, the level of the high-frequency signal after increasing the impedance Z ₁ , specifically, the detected current (detected current I ₁ , detected current I ₂ ) by the detector 109 and the detected current (detected current I ₂ ) before the increase. ₀ , the detection current I ₁ ), it is determined whether to increase or decrease the impedance Z ₁ .

  That is, according to the wireless communication unit 100, it is possible to adapt to changes in the characteristic impedance of the antenna 13 while having a simple configuration with the detector 109 and the matching circuit control unit 111 that controls the matching circuit 103.

(2) Second Embodiment In the second embodiment, a mobile terminal that detects a change in antenna characteristic impedance based on a resonance frequency of the antenna, that is, a shift in the center frequency of a radio signal received via the antenna will be described. . Specifically, (2.1) functional block configuration of the wireless communication unit, (2.2) operation of the wireless communication unit, and (2.3) operation / effect will be described.

(2.1) Functional Block Configuration of Radio Communication Unit Also in this embodiment, a mobile terminal having the same shape as the mobile terminal 10 according to the first embodiment (see FIG. 1) is used. In the present embodiment, a wireless communication unit 100A is provided instead of the wireless communication unit 100 (see FIG. 2) according to the first embodiment.

  FIG. 4 is a functional block configuration diagram of the wireless communication unit 100A. As illustrated in FIG. 2, the wireless communication unit 100A includes a duplexer 101, a matching circuit 103, a high-frequency amplifier circuit 107, a reception level measurement unit 113, and an antenna control unit 115.

  The duplexer 101, the matching circuit 103, and the high frequency amplifier circuit 107 have the same functions as those of the functional block provided in the wireless communication unit 100 according to the first embodiment. The matching circuit 103 is directly connected to the high frequency amplifier circuit 107.

  The reception level measuring unit 113 measures the reception level of the high frequency signal input to the high frequency amplifier circuit 107. In the present embodiment, the reception level measurement unit 113 constitutes a measurement unit.

Specifically, as shown in FIG. 6, the reception level measurement unit 113 measures a received signal code power (RSCP) at a reference frequency (frequency f ₀ ) based on the resonance frequency of the antenna 13.

Further, the reception level measurement unit 113 measures RSCP at an offset frequency (frequency f ₁ , frequency f ₂ ) that is a predetermined frequency away from the reference frequency. The frequency f ₂ (high offset frequency) is higher than the frequency f ₀ , and the frequency f ₁ (low offset frequency) is lower than the frequency f ₀ . In the present embodiment, the difference between the frequency f ₀ and the frequency f ₂ and the difference between the frequency f ₀ and the frequency f ₁ are each set to 2.5 MHz.

  Reception level measurement section 113 outputs the measured RSCP to antenna control section 115 at predetermined time intervals.

The antenna control unit 115 controls the resonance frequency of the antenna 13. Specifically, the antenna control unit 115 determines that the reception level (RSCP) at the offset frequency (frequency f ₁ or frequency f ₂ ) measured by the reception level measurement unit 113 is higher than the reception level at the reference frequency (frequency f ₀ ). Is higher, the resonance frequency of the antenna 13 is shifted in the direction of the reference frequency by controlling the antenna 13.

In the present embodiment, the antenna control unit 115 shifts the resonance frequency of the antenna 13 in the direction of the reference frequency based on the reception level at the frequency f ₂ (high offset frequency) and the frequency f ₁ (low offset frequency).

For example, as shown in FIG. 6, as the characteristic impedance of the antenna 13 changes, the resonance frequency of the antenna 13, specifically, the center frequency of the radio signal received via the antenna 13 is the frequency f _0. When it changes to F ₀ ′, the reception level at the frequency f ₂ becomes the maximum. The antenna control unit 115 controls the antenna 13 so that the center frequency of the radio signal received via the antenna 13 is lowered. A specific method for controlling the resonance frequency of the antenna 13 will be described later.

(2.2) Operation of Radio Communication Unit Next, an operation in which the radio communication unit 100A controls the resonance frequency of the antenna 13 will be described. FIG. 5 shows an operation flow in which the wireless communication unit 100A controls the resonance frequency of the antenna 13. As shown in FIG. 5, in step S210, the radio communication unit 100A measures the reception level (RSCP) at the reference frequency (frequency f ₀ ) and the offset frequency (frequency f ₁ , frequency f ₂ ).

  In step S220, the radio communication unit 100A determines a frequency at which RSCP is maximum.

When the RSCP of the frequency f ₁ is the maximum (f _{1 in} step S220), in step S230, the wireless communication unit 100A controls the antenna 13 to increase the center frequency (frequency F ₀ ′).

When the RSCP of the frequency f ₂ is the maximum (f _{2 in} step S220), in step S240, the radio communication unit 100A controls the antenna 13 and decreases the center frequency (frequency F ₀ ′).

When the RSCP of the frequency f ₀ is the maximum (f _{0 in} step S220), in step S250, the radio communication unit 100A maintains the current center frequency.

The wireless communication unit 100A until RSCP of the frequency _{f 0} becomes the maximum, and repeats the processing of step S210～S250.

(2.3) Action / Effect According to the wireless communication unit 100A, the high-frequency signal at the reference frequency (frequency f ₀ ) based on the resonance frequency of the antenna 13 and the offset frequency (frequency f ₁ or frequency f ₂ ). RSCP is measured by the reception level measurement unit 113.

  For this reason, it is possible to detect a change in the resonance frequency of the antenna 13 due to a change in the characteristic impedance of the antenna 13 according to the usage state of the mobile terminal. Further, when the RSCP of the high frequency signal at the offset frequency is higher than the RSCP at the reference frequency, the resonance frequency is shifted in the direction of the reference frequency by controlling the antenna 13.

  That is, according to the mobile terminal provided with the wireless communication unit 100A, it is possible to suppress the deterioration of the transmission / reception performance by detecting the characteristic change of the antenna 13 that changes according to the use state and adapting to the changing characteristic of the antenna 13. .

  In this embodiment, the reception level at the frequency f2 higher than the reference frequency (frequency f0) and the frequency f1 lower than the reference frequency is measured. For this reason, the change of the resonance frequency of the antenna 13 can be brought closer to the reference frequency more quickly.

(3) Other Embodiments As described above, the contents of the present invention have been disclosed through the first embodiment and the second embodiment of the present invention. However, the description and the drawings constituting a part of this disclosure limit the present invention. It should not be understood to be. From this disclosure, various alternative embodiments will be apparent to those skilled in the art.

For example, in the first embodiment, the detector 109 when a high frequency signal is detected, first, had increased impedance Z ₁ of the antenna 13 may reduce the impedance Z ₁ of the antenna 13.

  Although the circulator 105 is used in the first embodiment, an isolator may be used instead of the circulator 105.

  In the second embodiment, a plurality of offset frequencies of the frequency f1 and the frequency f2 are used. However, any one of the offset frequencies may be used.

  In the second embodiment, the reception level measurement unit 113 measures RSCP, but it does not necessarily have to be RSCP, and any other value may be used as long as it is a value indicating the reception level of the high-frequency signal.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

10 ... mobile terminal, 11 ... main body, 12 ... liquid crystal display unit, 13 ... antenna, 100, 100A ... wireless communication unit, 101 ... duplexer, 103 ... matching circuit, 105 ... _circulator 105 1-105 3 _... terminal, 107 DESCRIPTION OF SYMBOLS ... High frequency amplifier circuit, 109 ... Detector, 111 ... Matching circuit control part, 113 ... Reception level measurement part, 115 ... Antenna control part

Claims (3)

A mobile terminal equipped with an antenna,
A measurement unit for measuring a reception level of the high-frequency signal at a reference frequency based on a resonance frequency of the antenna and an offset frequency separated from the reference frequency by a predetermined frequency;
Antenna control for shifting the resonance frequency in the direction of the reference frequency by controlling the antenna when the reception level at the offset frequency measured by the measurement unit is higher than the reception level at the reference frequency A mobile terminal. The measurement unit measures a reception level at a high offset frequency higher than the reference frequency and a low offset frequency lower than the reference frequency as the offset frequency,
The mobile terminal according to claim 1, wherein the antenna control unit shifts the resonance frequency in the direction of the reference frequency based on the reception level at the high offset frequency and the low offset frequency. An antenna control method in a mobile terminal equipped with an antenna,
Measuring a reception level of the high-frequency signal at a reference frequency based on a resonance frequency of the antenna and an offset frequency separated from the reference frequency by a predetermined frequency;
Antenna control comprising: shifting the resonance frequency in the direction of the reference frequency by controlling the antenna when the reception level at the measured offset frequency is higher than the reception level at the reference frequency. Method.

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