JP2009272907A - Radio communication terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress harmonic components by utilizing an antenna unused in a second mode, in a dual mode mobile phone terminal which is usable by switching a first mode utilizing a diversity reception function and the second mode unutilizing the diversity reception function. <P>SOLUTION: In the second mode unutilizing the diversity function, a matching circuit 15 is connected to a sub antenna 12. The matching circuit 15 has a resonance frequency which causes the sub antenna 12 to interfere with the harmonic component of transmitted wave of the main antenna. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless communication terminal that can be used by switching between a first mode that uses a diversity reception function and a second mode that does not use a diversity reception function.

  Conventionally, a plurality of antennas are provided in a wireless communication terminal device (also simply referred to as a wireless communication terminal) such as a portable wireless device, and the antennas are switched according to the reception status of each antenna, or the weight of the combination of both received signals is changed. Therefore, there is a diversity system that improves reception characteristics.

When multiple antennas are built in a wireless communication terminal, if there are multiple antennas that are tuned in the same frequency band, characteristic deterioration due to interference will occur, so that inactive antennas will not be affected. Measures such as controlling the impedance are taken. For example, in the “antenna diversity digital portable radio device” described in Patent Document 1, an antenna that is not used is terminated without reflection by a switch, so that the impedance of the antenna that is used is not disturbed, and the radiation efficiency and radiation of the antenna are not disturbed. Techniques have been proposed that do not affect the pattern.
Japanese Patent Laid-Open No. 08-8797

  By the way, a dual-mode mobile phone terminal capable of switching and using different communication systems is known. Usually, in the dual mode, the radio bands used in both modes are different.

  For example, a so-called dual mode terminal is known in which the first mode is a mode that uses the diversity reception function using the first and second antennas, and the second mode is a mode that does not use the diversity reception function. Examples of the first mode include a CDMA (Code Division Multiple Access) 2000 1xEV-DO system, and examples of the second mode include a GSM (Global System for Mobile communications) system.

  In the GSM system or the like, since the transmission power is relatively large, it is necessary to satisfy the standard by sufficiently attenuating the harmonic component of the transmission wave from the mobile phone terminal used for communication.

  However, in the development stage of mobile phone terminals, harmonic components can often be attenuated sufficiently by measurement in the connector connection state, but cannot be attenuated by radiation measurement evaluation. Further, it is difficult to specify a site or a path that radiates harmonic components.

  The present invention has been made in such a background. In a dual mode wireless communication terminal that can be used by switching between a first mode that uses a diversity reception function and a second mode that does not use a diversity reception function, Provided is a wireless communication terminal capable of suppressing harmonic components using an antenna that is not used in the second mode.

  A radio communication terminal according to the present invention includes a main antenna for transmission and reception, a sub antenna dedicated for reception, a receiving circuit connected to both antennas, and a first mode for performing diversity reception using both antennas as an operation mode, and Control means for selecting one of the second modes using only the main antenna, a matching circuit for causing the sub-antenna to interfere with the harmonic component of the transmission wave of the main antenna in the second mode, and the control And a switching unit that switches the sub antenna to be connected to the receiving circuit in the first mode and to be connected to the matching circuit in the second mode in accordance with control of the means.

  The matching circuit is for causing the sub-antenna to interfere with a harmonic component of a transmission wave of the main antenna in the second mode, and connecting the sub-antenna to the matching circuit by the switching unit in the second mode. This suppresses the generation of harmonic components of the transmission wave of the main antenna.

  Another wireless communication terminal according to the present invention is a first antenna that performs diversity reception using both antennas as a main antenna for transmission and reception, a reception-only sub-antenna, a receiving circuit connected to both antennas, and an operation mode. Control means for selecting one of a mode, a second mode that uses only the main antenna, and a third mode that uses the same upstream band and downstream band as the first mode but does not perform diversity reception; A matching circuit that causes the sub-antenna to interfere with a harmonic component of a transmission wave of the main antenna in the second mode, and tuning or non-reflecting in the third mode when the tuning frequency deviates from the tuning frequency of the main antenna. The sub-antenna is received in the first mode according to the termination circuit that terminates and the control of the control means. Connect the road, connected to the matching circuit to the second mode, in which a switching unit for switching to connect to the termination circuit when said third mode.

  This wireless communication terminal has a third mode that uses the same uplink band and downlink band as the first mode but does not receive diversity reception as another operation mode, and is switched by the switching unit during the third mode. By connecting the sub-antenna to the termination circuit, the sub-antenna is tuned or de-reflected when it deviates from the tuning frequency of the main antenna. This prevents the sub antenna from interfering with the main antenna in the third mode.

  Still another radio communication terminal according to the present invention includes a main antenna for transmission and reception, a sub-antenna dedicated for reception, a receiving circuit connected to each of the antennas, and an operation mode for performing diversity reception using both antennas. And a control means for selecting one of the second mode using only the main antenna, and the sub-antenna is at least a first frequency of a downstream band in the second mode, or The antenna characteristic has a resonance frequency at a second frequency in the same frequency band as the harmonic component of the transmission wave of the main antenna.

  In this way, the sub-antenna has an antenna characteristic having a resonance frequency at least at the first frequency or the second frequency, thereby generating a harmonic component of the transmission wave of the main antenna in the second mode. Is suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the harmonic component of the transmission wave which becomes a problem in the mode which does not use the diversity reception function of a dual mode radio | wireless communication terminal can be effectively utilized, and the antenna which is not used can be suppressed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, a mobile phone terminal will be described as an example of a wireless communication terminal.

  FIG. 1 shows a first mode that uses a diversity reception function using the first and second antennas and a second mode that does not use the diversity reception function as operation modes of the mobile phone terminal in the present embodiment. The schematic structure of the antenna related part of the dual mode mobile phone terminal 10 that can be used by switching is shown. The first mode is a CDMA system that uses a diversity reception function, and the second mode is a TDMA system that does not use a diversity reception function such as GSM.

  The mobile phone terminal 10 includes a main antenna 11 for transmission / reception and a sub antenna 12 dedicated for reception. When the diversity reception function is used, both antennas are used. When the diversity reception function is not used, only the main antenna 11 is used, and the sub antenna 12 is inactive.

  The sub-antenna 12 is selectively connected to the receiving circuit 18 or the matching circuit 15 by a switch 16 (switching unit). That is, the sub-antenna 12 is connected to the receiving circuit 18 as shown in FIG. 1 in the first mode using the diversity receiving function, and matched as shown in FIG. 2 in the second mode not using the diversity receiving function. Connected to the circuit 15. The matching circuit 15 can be composed of an LC circuit including an inductor and a capacitor having a predetermined constant. The reception circuit 18 is for diversity reception, and a reception circuit (not shown in FIG. 1) on the main antenna 11 side may also exist.

  In the second mode illustrated in FIG. 2, transmission power larger than that in the first mode is generally used. Therefore, the harmonic component 13 is inevitably radiated from the part 14 of the mobile phone terminal. This harmonic component 13 needs to be reduced by some method. On the other hand, a harmonic component at a level that causes a problem in the first mode does not occur.

  FIG. 3 is an explanatory diagram of the use band and harmonics when the second antenna, that is, the diversity reception function is not used and the sub-antenna is inactive.

  The frequency band of the radio wave used in the mobile phone terminal includes an upstream band including a transmission wave from the terminal to the base station and a downstream band including a reception wave from the base station to the terminal. Further, second and third harmonics are generated as radiation having twice and three times the frequency of the transmitted wave.

  In the present embodiment, by connecting a predetermined matching circuit 15 to the sub-antenna 12 that is not used in the second mode in which such harmonic components are generated, the transmission wave is transmitted using the presence of the sub-antenna 12. This suppresses (attenuates) harmonic component radiation. For this purpose, the resonance frequency of the matching circuit 15 is made to coincide with at least one (preferably both) of the second harmonic and the third harmonic, thereby intentionally setting the sub-antenna 12 to the second and / or second harmonics. Or it interferes with the third harmonic. As a result, the radiation efficiency of the portion that radiates the harmonic component deteriorates due to the interference of the sub-antenna. That is, the radiant power of the harmonic component is reduced.

  The technique as described in Patent Document 1 prevents the sub antenna from interfering with the transmission wave and exerts an adverse effect. However, in the present invention, by directing such an interference destination to the harmonic, Rather, it takes advantage of the nature of such interference.

  FIG. 4 is a diagram showing a schematic configuration of a portion related to the present invention of the mobile phone terminal 10. Elements similar to those in FIGS. 1 and 2 are denoted by the same reference numerals, and redundant description is omitted.

  The cellular phone terminal 10 includes a transmission / reception circuit 30 for the first mode that uses the diversity reception function, a transmission / reception circuit 20 for the second mode that does not use the diversity reception function, and a switch for switching between the two modes. In addition to the mode switching unit 19 such as a diplexer and the switching control of the mode switching unit 19, a control unit 40 that controls the entire mobile phone terminal 10 is provided.

  The transmission / reception circuit 30 includes a transmission circuit 22 for the second mode, a reception circuit 23, and an antenna duplexer 21 for sharing the main antenna 11 in both circuits.

  The transmission / reception circuit 30 includes a transmission circuit 32 for the first mode, a first reception circuit 33 that receives a reception signal from the main antenna 11, an antenna duplexer 31 for sharing the main antenna 11 in both circuits, and a sub-antenna. 12 includes a second reception circuit 34 that receives a reception signal from the signal 12. The second receiving circuit 34 corresponds to the receiving circuit 18 shown in FIGS.

  Here, the diversity reception function is assumed to be a type in which reception signals of two reception circuits corresponding to reception states of a plurality of antennas are combined to change the weights of both antennas. For this purpose, other circuits such as a circuit for synthesizing both received signals after amplification processing by the first and second receiving circuits 33 and 34 are not shown.

  Next, another embodiment will be described.

  The mobile phone terminal 10 can also be provided with a third mode that uses the same uplink band and downlink band as the first mode but does not use the diversity reception function as another operation mode. As in the previous embodiment, it is assumed that the harmonics of the transmission wave are not a problem in the first mode. In such a case, as shown in FIG. 5, in order to prevent the unused sub antenna 12 from interfering with the main antenna 11 in the third mode, the sub antenna 12 is connected to the termination circuit 51 by the switch 16. To do. The sub-antenna 12 is impedance controlled by the termination circuit 51 so as not to affect the main antenna. Specifically, the switch 16 connects the sub-antenna and the LC circuit so that the tuning is performed when the tuning frequency deviates from the tuning frequency of the main antenna. Alternatively, the termination circuit 51 may be non-reflective terminated at the open portion of the switch, similar to that described in Patent Document 1.

  FIG. 6 is a diagram showing a schematic configuration of a portion related to the present invention of the mobile phone terminal 10 in the second embodiment. The same elements as those in FIG. 4 are denoted by the same reference numerals, and redundant description is omitted.

  In FIG. 6, a switch 50 that selectively connects the sub-antenna 12 to any one of the second receiving circuit 34, the matching circuit 15, and the termination circuit 51 is provided. The control unit 40 switches the switch 50 according to the switching between the first to third modes.

  FIG. 7 is a diagram showing a schematic configuration of a portion related to the present invention of the mobile phone terminal 10 according to the third embodiment. The same reference numerals are given to the same elements as those in the other drawings described above, and a duplicate description will be omitted.

  In the configuration of FIG. 7, as the characteristics of the antenna itself, the first mode, the second mode, and the third mode of the second mode transmission wave in the first mode, A sub-antenna 70 having a third resonance frequency is used. Due to such antenna characteristics of the sub-antenna 70, harmonic radiation can be suppressed in the second mode in which the sub-antenna 70 is in an inactive state.

  The preferred embodiments of the present invention have been described above, but various modifications and changes other than those mentioned above can be made. For example, although the diversity reception of the type in which the reception signals of two reception circuits according to the reception status of a plurality of antennas are combined and the weights of both antennas are changed has been described, Good.

It is a figure which shows schematic structure of the 1st mode of the dual mode mobile telephone terminal in embodiment of this invention. It is a figure which shows schematic structure of the 2nd mode of the dual mode mobile telephone terminal in embodiment of this invention. In embodiment of this invention, it is explanatory drawing of a use band and a harmonic when not using a diversity reception function. It is the figure which showed schematic structure of the part relevant to this invention of a mobile telephone terminal. It is explanatory drawing of the 2nd Embodiment of this invention. It is the figure which showed schematic structure of the part relevant to this invention of the mobile telephone terminal in the 2nd Embodiment of this invention. It is the figure which showed schematic structure of the part relevant to this invention of the mobile telephone terminal in the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Mobile phone terminal, 11 ... Main antenna, 12 ... Subantenna, 13 ... Harmonic component, 14 ... Part of mobile phone terminal, 15 ... Matching circuit, 16 ... Switch, 18 ... Receiving circuit, 19 ... Mode switching part , 20 ... transmission / reception circuit, 21 ... antenna duplexer, 22 ... transmission circuit, 23 ... reception circuit, 30 ... transmission / reception circuit, 31 ... antenna duplexer, 32 ... transmission circuit, 33, 34 ... reception circuit, 40 ... control unit, 50 ... Switch, 51 ... Termination circuit, 70 ... Sub antenna

Claims (5)

A main antenna for transmission and reception and a sub-antenna dedicated to reception;
Control means for selecting one of a first mode in which diversity reception is performed using both antennas and a second mode in which only the main antenna is used as an operation mode;
A matching circuit that causes the sub-antenna to interfere with a harmonic component of a transmission wave of the main antenna in the second mode;
A wireless communication terminal comprising: a switching unit configured to switch the sub-antenna to be connected to the receiving circuit in the first mode and to be connected to the matching circuit in the second mode according to the control of the control unit. A main antenna for transmission and reception and a sub-antenna dedicated to reception;
As an operation mode, a first mode in which diversity reception is performed using both antennas, a second mode in which only the main antenna is used, and the same upstream band and downstream band as in the first mode are used, but diversity reception is performed. Control means for selecting any of the non-third modes,
A matching circuit that causes the sub-antenna to interfere with a harmonic component of a transmission wave of the main antenna in the second mode;
A termination circuit that tunes away from the tuning frequency of the main antenna during the third mode, or terminates without reflection;
Depending on the control of the control means, the sub-antenna is connected to the receiving circuit in the first mode, connected to the matching circuit in the second mode, and connected to the termination circuit in the third mode A wireless communication terminal comprising a switching unit that switches to perform.   The wireless communication terminal according to claim 1 or 2, wherein a resonance frequency of the matching circuit is matched with a frequency of a harmonic component of a transmission wave of the main antenna in the second mode. A main antenna for transmission and reception and a sub-antenna dedicated to reception;
A control means for selecting one of a first mode in which diversity reception is performed using both antennas and a second mode in which only the main antenna is used as an operation mode;
The sub-antenna has an antenna characteristic having a resonance frequency at least at the first frequency in the downstream band in the second mode or the second frequency in the same frequency band as the harmonic component of the transmission wave of the main antenna. A wireless communication terminal.   The radio communication terminal according to any one of claims 1 to 4, wherein the first mode is a CDMA system that uses a diversity reception function, and the second mode is a TDMA system that does not use a diversity reception function.

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