JP3112464B2 - Portable wireless communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a portable wireless communication device that performs antenna diversity communication using an antenna selected from a plurality of antennas.

(Prior Art) Some portable wireless communication devices use conventional simple wireless communication or weak radio waves. In addition, some have been created that can access cellular cellular telephone networks. This is the 22nd
This will be described with reference to the drawings. The portable wireless communication device 1102 transmits and receives radio waves to and from a wireless base station (station D) 1101. The D station 1101 is connected to a general home telephone or the like via a public telephone network (not shown) by wire. A distribution of a current flowing through an antenna attached to such a portable wireless communication device will be considered.

FIG. 23 (a) shows a current distribution 12 when a high-frequency current 1202 is supplied to a half-wavelength dipole 1201 used as a standard.
Indicates 03.

In the case of a monopole 1204 having a length λ / 4 (where λ represents the wavelength of a radio carrier) with a ground plate 1205 shown in FIG.
A current distribution 1206 is shown for imaging by 05. This is the 23rd
It is almost the same as a half-wavelength dipole as shown in FIG.

Note that a portable wireless communication device is required to be miniaturized because it is usually used by a user in a hand. Therefore, a physically small antenna is required. For this reason, an antenna of a type built in a housing of a portable wireless communication device is often used. Therefore, it is used for a portable wireless communication device. The length of the antenna is often smaller than λ / 4.

In the case where the physical length of the antenna is short, there is an example considered from the results of measurement experiments on an actual portable wireless communication device (Sekine, Maeda, "Handset affecting the radiation field of antenna of portable wireless device" And Influences and Countermeasures of Curl Code, "IEICE Technical Report, AP89-41, September 1989.)

In the portable wireless communication device handled in this example, as shown in FIG. 24, a built-in normal mode helical antenna 1301 having a shorter length than the portable wireless communication device housing is perpendicular to the long axis direction of the housing. Attached to. This is shown in FIG. The length of this antenna is 30
Less than one part, very short compared to λ / 4. Circuit board ground and metal chassis 1302 inside portable radio
Is directly connected to the negative pole of the battery 1303 serving as a power supply. The ground of the circuit board inside the portable wireless communication device and the length of the metal chassis 1303 are longer than those of the normal mode helical antenna 1301. One end of a feed point of the normal mode helical antenna 1301 is connected to the ground 1303 of the circuit board.

The measurement result of the full solid angle radiation pattern of the portable wireless communication device is as shown in FIG. 25 (b). For comparison, the results of measuring the full solid angle radiation pattern of the dipole antenna 1320 fixed in the direction shown in FIG. 26A using the same apparatus as shown in FIG. b)
Shown in Looking at the results, it can be seen that the results of FIG. 25 (b) and FIG. 26 (b) are very similar.

Normally, the normal mode helical antenna 1301 mounted in the direction shown in FIG. 24 radiates radio waves like a dipole antenna fixed vertically in the direction shown in FIG. 23 (c). The result in FIG. 25 (c) is a result that is inconsistent with the radiation characteristics that are usually considered. Therefore, it is presumed that the radiation from the built-in normal mode helical antenna 1301 shown in FIG. 24 is extremely small regardless of the impedance matching.

Considering these measurement results, it is estimated that the high-frequency current distribution 1210 of the portable wireless communication device is as shown in FIG. 23 (c). In other words, since the circuit board (especially ground) or the chassis 1302 covering the circuit board in the portable wireless communication device having a larger physical length than the normal mode helical antenna 1301 has a larger radiation resistance,
A high-frequency current flows through the circuit board or the chassis 1302, and a radio wave is radiated or received from the circuit board or the chassis 1302. In addition, the physical length of the circuit board and chassis 1302 is the normal mode helical antenna
Since it is larger than 1301, most of the radio wave radiation or reception depends on the high-frequency current flowing through the circuit board and the chassis 1301.

The above-mentioned phenomenon is caused by the built-in normal mode helical antenna 1301 and the circuit board or chassis as described above.
It is estimated to be due to the physical length relationship with 1302. Therefore, a phenomenon that generally occurs in portable wireless communication devices that often use a physically short built-in antenna,
It is considered an unavoidable phenomenon.

On the other hand, antenna diversity reception which receives received signals from a plurality of antennas and switches the antennas so as to receive the received signal from the antenna having the best reception state, or combines received signals from a plurality of antennas and uses the combined signals as received signals. Also, antenna diversity transmission in which radio waves are transmitted from a plurality of antennas is often used to improve the quality of wireless communication. This is to prevent the presence of many reflections and interference waves between the D station 1101 and the portable wireless communication device 1102 shown in FIG.

In order to provide a portable wireless communication device with a plurality of antennas used for performing antenna diversity communication, the size of the antenna is further restricted as compared with the case where a single antenna is used. Therefore, an antenna of a type built in a housing is often used as a part or all of a plurality of antennas.

Based on such a demand, if a plurality of antennas having a length shorter than λ / 4 are attached, as described in FIG. The flowing part becomes a single circuit board or chassis. Therefore, the radiation characteristics of multiple antennas are
It will be very similar. Therefore, the correlation between the plurality of antennas becomes large. Therefore, the characteristics of an antenna used for performing antenna diversity communication (hereinafter, referred to as antenna diversity branch) may not be desirable.

(Problems to be Solved by the Invention) As described above, in a conventional portable wireless communication device, when power is supplied to an antenna, a high-frequency current is applied to a circuit board in the portable wireless communication device or a chassis covering the circuit board. flow,
Since a radio wave is radiated from the circuit board, there is a problem that, when a plurality of antennas are used, there is little difference in radiation characteristics, and it is difficult to obtain a desirable correlation characteristic as a diversity branch. Therefore, an object of the present invention is to eliminate the above-mentioned disadvantages of the prior art and to provide a portable wireless communication device including a plurality of antenna diversity branches having good correlation characteristics.

[Configuration of the invention]

(Means for Solving the Problems) In order to achieve the above-described object, a portable wireless communication device according to the present invention includes two housings that are rotatable at one connection unit, and includes a transmission unit and a reception unit. In a portable radio communication device comprising: a first and a second antenna installed in each of the two housings, a receiving unit connected to these first and second antennas, A selection switching unit for selectively switching the first and second antennas.

Further, in the portable wireless communication device of the present invention, the first and second housings rotatably connected, the first antenna provided in the first housing, and the second housing The provided second antenna, the transmission unit and the reception unit connected to the first and second antennas, and a selection switching unit that selectively switches the first and second antennas according to reception quality It is characterized by the following.

Further, in the portable wireless communication device of the present invention, the selection switching unit compares the reception signal levels of the first and second antennas, and selects the first reception signal having a higher reception signal level. The second antenna is switched.

Further, in the portable wireless communication device of the present invention, the selection switching unit is configured to convert the first,
The detection levels of the reception signals of the second antenna are compared, and the first and second antennas are switched so as to select the reception signal having the higher detection level.

Further, in the portable wireless communication device of the present invention, the first,
The second antenna is characterized by being constituted by different types of antennas.

Further, in the portable wireless communication device of the present invention, the first,
At least one of the second antennas is configured by one of an inverted F-shaped antenna, a helical antenna, and a rod antenna.

(Operation) According to the above-described configuration, the two rotatable one connection part can be used.
In a portable wireless communication device including two housings and having a transmitting unit and a receiving unit, the first and second antennas are installed in each of the two housings, so that the difference in the radiation characteristics of each antenna is obtained. Can be increased.
Therefore, it is possible to configure an antenna diversity branch having a small correlation characteristic suitable for performing diversity communication.

This is a portable device including first and second housings rotatably connected, a first antenna provided on the first housing, and a second antenna provided on the second housing. The same applies to a wireless communication device. By adopting such a configuration, it is possible to efficiently switch the first and second antennas according to the reception quality.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a view in which a portable wireless communication device is folded,
Chassis 102 and 103 are connected by a connection part 101.

FIG. 2 is an expanded view of the portable wireless communication device of FIG. The speaker unit 104 outputs the received voice. The microphone section 105 is for inputting voice.
The keypad unit 106 is for inputting the telephone number of the other party. The display unit 107 displays a usage state of the portable wireless communication device, an input from the keypad unit 106, and the like. For example, a liquid crystal is used. Note that some models that do not require display do not have this. The speaker unit 104, the microphone unit 105, and the keypad unit 106 do not come into contact with each other even when the portable wireless communication device is folded as shown in FIG. This is because, for example, the housings 102 and 103 are concave. Therefore, no breakage occurs, and the size of the portable wireless communication device can be reduced.

FIG. 5 is a block diagram of a portable wireless communication device according to the present invention. Signals received by the first antenna 121 and the second antenna 122 are separated into voice information and character information by a voice information character information selection unit 160 via a transmission / reception unit 150. As a result,
If the received signal is audio information, it is processed by the audio information processing unit 161 and the speaker unit 104 outputs audio. If the received signal is character information, the received signal is converted into character information by character information processing section 162 and displayed on display section 107. Next, if a voice is input from the microphone unit 105, the voice from the microphone unit 105 is processed by the voice information conversion unit 170. Then, the audio signal is transmitted from the first antenna 121 and the second antenna 122 via the transmission / reception unit 150. The control section 180 controls each section. It is preferable that the connection lines used for connection of the respective parts generate as little noise as possible.

FIG. 3 is a perspective view of the portable wireless communication device of FIG. Here, an inverted F-shaped antenna is used for the first antenna 121 and the second antenna 122.

As a reason for using the inverted F-shaped antenna, a portable wireless communication device is usually worn by a user or used in a hand. In other words, it is used near the main plate. According to a study on the radiation characteristics when an inverted F-shaped antenna is installed on the housing (Tsunekawa et al., "Study on the characteristics of a flat inverted F-shaped antenna considering the housing of a portable wireless device", 1985 In addition to the radiation expected from a dipole that is perpendicular to the flat radiating element, which is expected, the same radiation as a dipole parallel to the radiating element is observed. In the latter radiation, it is presumed that a high-frequency current is flowing through the housing of the portable wireless communication device, or the chassis or circuit board inside the housing, in consideration of the study described above with reference to FIG.

In this example, a first antenna 121 and a second antenna 122
Are connected to separate circuit boards 110 and 111, respectively. The circuit boards 110 and 111 are covered with different chassis 102 and 103, respectively.

Therefore, the distributions 130 and 131 of the high-frequency current flowing through the circuit boards 110 and 111 or the chassis 102 and 103 when power is supplied to the respective antennas 121 and 122 are spatially different as shown in FIG. Therefore, different radiation characteristics corresponding to the high-frequency current distribution can be obtained. As a result, a plurality of antenna diversity branches having a small correlation can be obtained.

Here, the diversity before detection and the diversity after detection will be described. First, the block diagram of diversity before detection
This is shown in FIG. First antenna 801, second antenna
The level of the signal received by the
Detected at 3,804. The comparison switching unit 805 compares the detection levels of the level detectors 803 and 804, and sends a reception signal having a higher detection level to the reception unit 806. Receiving section 806 converts the signal received from comparison switching section 805 into a baseband signal.

Next, Fig. 19 (b) is a block diagram of diversity after detection.
Shown in The reception signals of the first antenna 811 and the second antenna 812 are converted into baseband signals by the reception units 813 and 814, respectively. The receiving units 813 and 814 detect the levels of the baseband signals with the level detectors 815 and 816, respectively.
The comparison switching unit 817 compares the detection levels of the level detectors 815 and 816, and outputs a baseband signal having a higher detection level.

As described above, comparison (selection) is easier when diversity after detection is used than when diversity before detection is used. This is the same for the composition. The reason for this is that the signal handled by the post-detection diversity comparison switching unit 817 is a baseband signal, and the pre-detection diversity comparison switching unit is used.
This is because the signal handled by the 805 is based on a lower frequency circuit stage. For this reason, even when ferrite or the like is used for the line through which the received signal passes to increase the resistance and avoid high-frequency mutual coupling, the result is greater for diversity after detection.

FIG. 6 shows a second embodiment of the portable wireless communication device according to the present invention.

FIG. 6 shows a case in which different types of antennas are used for a diversity communication when applied to a foldable portable wireless communication device similar to FIG. 2 of the first embodiment. Things.

As a difference from FIG. 3, the first antenna 201 includes:
A normal mode helical antenna is used for the inverted F-shaped antenna and the second antenna 202. Otherwise third
Based on the figure.

When the normal mode helical antenna with a built-in housing is used, the circuit boards 110, 11
Most of the emission or reception of radio waves depends on the high-frequency current flowing through the chassis 1 and the chassis 102 and 103.

Therefore, the distribution of the high-frequency current flowing through the circuit boards 101 and 111 or the chassis 102 and 103 when power is supplied to the respective antennas 201 and 202 is spatially different as shown in FIG. Therefore, different radiation characteristics corresponding to the high-frequency current distribution can be obtained. As a result, a plurality of antenna diversity branches having a small correlation can be obtained.

In addition, by using different types of antennas, it is possible to configure a portable wireless communication device that makes use of each feature. For example, the inverted F-shaped antenna as the first antenna 201 takes a certain amount of space in the portable wireless device because the size of the radiating element is determined by the transmission or reception frequency, but a normal mode helical antenna as the second antenna 202 Since no space is required, a space for accommodating a battery or the like as the power supply unit 220 can be provided on the chassis 103 side where the normal mode helical antenna as the second antenna 202 is attached. This is shown in FIG. FIG. 7 considers diversity after detection. That is, as shown in FIG. 19 (b), in the case of the diversity after detection, each of the plurality of antennas has a receiving unit. Usually, the receiving unit requires more current than the control unit that controls signals and the like by the receiving unit. However, in the case of performing the pre-detection diversity shown in FIG. 19 (a), only one receiver is required for a plurality of antennas. Therefore, the portable wireless communication device shown in FIG. 7 can also have a configuration as shown in FIG. This is a case where the chassis 102 has a control unit (not shown). This control does not require much current. FIG. 8 shows that the mercury battery 230 and the like are arranged on the chassis 102 so that the problem that noise or the like is generated in the transmission process when the current is supplied from the power supply unit 220 is not generated. The mercury battery 230 is connected to the control unit.

FIG. 9 shows an inverted F-shaped antenna as the first antenna 201 and a normal mode helical antenna as the second antenna 202 in FIG.
This is implemented in 2. The rod antennas 301 and 302 are connected to circuit boards 110 and 111, respectively. FIG. 10 shows a circuit board 310 in which rod antennas 301 and 302 are installed at intervals. When power is supplied to the rod antennas 301 and 302, they are distributed at spatially separated positions. For this reason,
Different radiation characteristics corresponding to the current distribution are obtained. As a result, a plurality of antenna diversity branches having a small correlation can be obtained.

Next, FIG. 11 shows an external view of the portable wireless communication device. The speaker unit 104, the microphone unit 105, and the keypad unit 106
It is the same as FIG. Further, similarly to FIG. 2, the portable wireless communication device may be provided with a display unit for informing a user of a use state and the like. It is preferable that the connection lines used for connection of the respective parts generate as little noise as possible. Therefore, they are usually connected by a microstrip line or the like.
FIG. 12 shows a perspective view of FIG. As shown in FIG.
The first antenna 401 and the second antenna 402 are connected to separate circuit boards 410 and 411, respectively, which are separately located. Therefore, each antenna 401,40
When power is supplied to 2, the current is distributed at spatially separated positions. Therefore, current distributions 420 and 421 as shown in FIG. 13 are obtained.

FIG. 14 is a perspective view of a portable wireless communication device. This is because the first antenna 501 and the second antenna 502 are different from each other on the circuit board 51 on which different components are placed at remote positions.
0,511. Further, the circuit boards 510, 511
Are provided with notches 520 and 521 of the ground pattern at positions different from the other.

Therefore, when power is supplied to each of the antennas 501 and 502, the current is distributed at spatially separated positions, and current components in directions different from each other become large. Thus, different radiation characteristics corresponding to the current distribution are obtained. As a result, a plurality of antenna diversity branches having a small correlation can be obtained. Also, by adjusting the size and length of the notches 520 and 521 in the ground pattern, it is possible to achieve matching as an antenna. Note that the sizes of the cuts 520 and 521 of the ground pattern can be variously changed.

FIG. 15 is a perspective view of a portable wireless communication device. This is because the first antenna 601 and the second antenna 602 are connected to the divided ground patterns 631 and 632 on the same circuit board 620. The ground patterns 631, 632 are elongated in directions orthogonal to each other.

Therefore, when power is supplied to each of the antennas 601, 602, current components in directions orthogonal to each other increase. Thus, different radiation characteristics corresponding to the current distribution are obtained. This current distribution is shown in FIG. This shows a current distribution 641 due to the first antenna 601 and a current distribution 642 due to the second antenna 602. As a result, a plurality of antenna diversity branches having a small correlation can be obtained.

FIG. 17 is a perspective view of a portable wireless communication device. This has chippings 721 and 722 of the ground pattern at different positions on the front and back of the same circuit board.
And the second antenna 702 are connected. Figure 18 shows Figure 17
It is the figure which looked at the figure from the back. As can be seen from FIGS. 17 and 18, each of the ground patterns 711 and 712 is provided with a notch 721 and 722 of the ground pattern at a position different from the other. When power is supplied to the first antenna 701 and the second antenna 702 by the lack of the ground patterns 721 and 722, the components of the high-frequency current flowing through the circuit board and the casing of the portable wireless communication device in directions different from each other increase. This is because the high-frequency current flowing through the ground patterns 711 and 712 changes due to the lack of the ground patterns 721 and 722.

Therefore, the two antennas 701 and 702 have different radiation characteristics corresponding to different current distributions.
As a result, a plurality of antenna diversity branches having a small correlation can be obtained. Also, the ground pattern is missing.
By adjusting the size and length of 2, it is possible to achieve matching as an antenna.

In the above example, the lack of ground pattern at different positions
Although the case where it is taken on the front and back of the circuit board on which the 721 and 722 are provided is given, it is considered that the same effect can be obtained when it is taken on different layers of the multilayer board.

The present invention is not limited to the embodiments described above. The antenna used to perform antenna diversity reception and transmission or both of them is not limited to an inverted-F antenna, a normal mode helical antenna, or the like. A loop antenna or the like can be used as another type of antenna. Although the above embodiment describes a portable wireless communication device used for transmitting and receiving to and from a wireless base station or the like, it can be used as a cordless telephone handset used at home.

In addition, portable wireless communication devices are required to be smaller and consume less power. Intermittent reception and battery saving are described as methods to satisfy this demand.
First, intermittent reception will be described. FIG. 20A shows a block diagram for performing intermittent reception. When the switch 903 is in the ON state, current is supplied from the power supply unit 905 to the transmission / reception unit 902 and the signal processing unit 907 via the control unit 904. At this time,
In the case of reception, the signal is received by a reception signal unit 902 from an antenna 901, and a signal processing unit 907 performs signal processing such as conversion to a baseband signal on the reception signal. In the case of transmission, a transmission signal is obtained by the transmission processing unit 907 and transmitted from the antenna 901 via the transmission / reception unit 902. Of course, when the switch 903 is in the OFF state, the transmitting / receiving unit 902 and the signal processing unit 907 do not operate. The operation time of the switch 903 depends on the output of the timer 906. FIG. 20 (b) shows the correspondence between the timer output, the current value and the time interval. Timer 906 is 2
Outputs signals at two time intervals. As an example, one time interval is 10 ms and the other time is 50 ms. First, the timer 90
Output the signal from 6. When the control unit 904 receives this signal, the switch 903 is turned on. Then, current is supplied from the power supply unit 905 to the transmission / reception unit 902 and the signal processing unit 907. Then 10ms
Thereafter, a signal is output from the timer 906. When the control unit 904 receives this signal, the control unit 904 turns off the switch 903. Further, within 50 ms, the timer 906 outputs a signal.
That is, the timer 906 outputs a signal at two time intervals. The control unit 904 turns on the switch 903 only for one time interval
At the other time interval, the switch 903 is turned off. As a result, it is not necessary to constantly supply current to the transmission / reception unit 902 and the signal processing unit 907. Therefore, current consumption of the power supply unit 905 can be suppressed, and the portable wireless communication device can be used for a long time.

Next, battery saving will be described. In the battery saving, the power supply from the power supply unit is suppressed as in the case of the intermittent reception, and the portable wireless communication device can be used for a long time. The difference from the intermittent reception is
The point is that reception is always performed. A block diagram for performing battery saving is shown in FIG.
The received signal received by antenna 1001 is a baseband processing unit
Entered in 1002. The baseband processing unit 1002 converts a signal received by the antenna 1001 into a baseband signal. The baseband signal from the baseband processing unit 1002 is compared by the comparison unit 1003 with the desired signal of the portable wireless communication device. As a result, if the received signal matches the desired signal, signal processing is performed. The power supply unit 1007 is connected to the baseband processing unit 1002 and the comparison unit 1003.
The power supply unit 1007 is connected to the signal processing unit 1004 via the switch 1005 and the control unit 1006. If the signal received by the comparing unit 1003 matches the desired signal, the comparing unit 1003
The control signal is sent to 1006 and the control unit 1006 turns on the switch 1005
To As a result, power is supplied to the processing units after the signal processing unit 1004. That is, power is supplied to the entire portable wireless communication device only when a desired signal is received. Therefore, the portable wireless communication device can be used for a long time as in the case of the intermittent reception. The portable wireless communication device according to the present invention is not limited to the above-mentioned intermittent reception and battery saving, but may be used if there is any other method for reducing power consumption.

〔The invention's effect〕

As described in detail above, according to the portable wireless communication device of the present invention, an antenna is installed in each of a plurality of casings that are rotatably connected by one connection portion, and the reception quality of those antennas is improved. By selectively switching the first and second antennas in response to the above, the difference in the radiation characteristics of the antennas installed in a plurality of housings can be increased, and the antenna diversity having a small correlation characteristic suitable for performing diversity communication. Branches can be obtained.

[Brief description of the drawings]

1 to 18 are diagrams for explaining a portable wireless communication device according to the present invention, FIG. 19 is a diagram used for explaining diversity reception, FIG. 20 is a diagram used for explaining intermittent reception, FIG. Is a diagram used for describing battery saving, FIG. 22 is a diagram showing a usage form of the portable wireless communication device, FIG. 23 is a diagram used for describing a current distribution of the portable wireless communication device, and FIG. 24 is used for an experiment. FIG. 25 and FIG. 26 are perspective views of the portable radio communication device, and show the results of experiments on the portable radio communication device. 121,201,301,401,501,601,701 ... first antenna 122,202,302,402,502,602,702 ... second antenna 110,111,410,411 ... circuit board 510,511,631,632,711,712 ... ground pattern

Continuation of front page (56) References JP-A-60-47502 (JP, A) JP-A-61-23423 (JP, A) JP-A-59-181732 (JP, A) JP-A-62-277803 (JP) JP-A-62-277801 (JP, A) JP-A-50-11612 (JP, U) JP-A-2-72032 (JP, U) JP-A-3-75639 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04B 1/08 H01Q 1/24 H04B 1/38 H04B 7/02 H04Q 7/36 H04B 1/16 H01Q 13/00

Claims (6)

(57) [Claims] 1. A portable wireless communication device comprising two housings rotatable at one connection portion and provided with a transmitting means and a receiving means, wherein a first wireless communication device is provided in each of the two housings. , A second antenna, a receiving unit connected to the first and second antennas, and a selection switching unit for selectively switching the first and second antennas according to reception quality. Portable wireless communication device. A first antenna provided in the first housing, a first antenna provided in the first housing, and a second antenna provided in the second housing. A transmission unit and a reception unit connected to the first and second antennas, and a selection switching unit for selectively switching the first and second antennas according to reception quality. Wireless communicator. 3. The selection switching section compares the reception signal levels of the first and second antennas and switches the first and second antennas so as to select a reception signal having a higher reception signal level. 3. The portable wireless communication device according to claim 1, wherein: 4. The apparatus according to claim 1, wherein the selection switching unit compares detection levels of the reception signals of the first and second antennas converted into baseband signals and selects the first reception signal having a higher detection level. 3. The portable wireless communication device according to claim 1, wherein the second antenna is switched. 5. The portable radio communication device according to claim 1, wherein said first and second antennas are respectively constituted by different types of antennas. 6. The mobile phone according to claim 1, wherein at least one of the first and second antennas is constituted by one of an inverted F-shaped antenna, a helical antenna, and a rod antenna. Type wireless communication device.