JPH09223993A - Antenna switching device and radio equipment using the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cope with the degradation of radiation characteristics by relatively easy design change by using an antenna switching device capable of flexibly coping with characteristic change by mutual coupling as well. SOLUTION: This antenna switching device 8 is provided with two first selection switch 9 and second selection switch 10 and the respective movable contact points 9a and 10a are connected to input terminals 5a and 5b. Also, a second fixed contact point 9c and a forth fixed contact point 10c are connected to an output terminal 5c, and the other first fixed contact point 9b and third fixed contact point 10b are respectively connected to load impedances 11a and 11b provided with prescribed reactances X1 and X2. The switching operation of the two selection switches 9 and 10 is linked and performed in a seesaw system. In this case, load reactance value is relatively easily changed by changing the load impedances 11a and 11b and thus, the characteristic change by the mutual coupling 15 optimally changeably designed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna switching device and a wireless device using the same, and more particularly to an antenna switching device used in a wireless device of a mobile communication system such as a mobile phone and a wireless device using the same. .

[0002]

2. Description of the Related Art In recent years, various mobile communication systems have been put to practical use, but in this kind of communication, deterioration of communication quality due to multipath fading is a serious problem, and various countermeasure techniques are applied to practical systems. Has been done. For example, in a mobile phone system, antenna diversity technology is adopted as a measure against multipath fading.

FIG. 3 is a diagram schematically showing a system configuration of a radio equipment adopting an antenna switching diversity system which can be realized with the simplest configuration among the antenna diversity techniques. The specific configuration will be described below. The first antenna 1 and the second antenna 2 are arranged spatially separated from each other. The interval is set to about 0.2 to 0.3 times the wavelength of the used frequency, and the spatially low correlation coefficient is set.

A first high-frequency transmission line 3 and a second high-frequency transmission line 4 are electrically connected to these two antennas, respectively, and received by the two antennas which are spatially separated from each other. It plays the role of collecting signals in one place. In addition, the ends of both of these high-frequency transmission lines 3 and 4 are
The input terminals 5a and 5b of the antenna switching device 5 are electrically connected to each other. The antenna switching device 5 is composed of only the selection switch 6 as shown in the figure, and has only the function of selectively switching the electrical connection of two input terminals with respect to one output terminal. The output terminal 5c of the antenna switching device 5 is electrically connected to the wireless circuit 7.

The radio system employing the antenna switching device 5 is constructed as described above and works as an effective countermeasure against multipath fading as described below. Normally, the selection switch 6 is tilted to the 5a1 side and the first antenna 1 is connected to the wireless circuit 7. When the strength of the signal received by the first antenna 1 is extremely reduced due to multipath fading, the selection switch 6 is switched to the 5a2 side, and the second antenna 2 is connected to the circuit 7 of the radio device. At this time, since the correlation coefficient of the reception signal strength of the second antenna 2 is extremely low, the probability that the reception signal strength of the first antenna 1 is extremely decreased simultaneously with the reception signal strength of the first antenna 1 is extremely low. In most cases, stable received signal strength is obtained.

Further, when the strength of the signal received by the second antenna 2 is extremely lowered, the selection switch 6 is again activated by 5a1.
The first antenna 1 is switched to the circuit 7 of the radio device.
Will be connected with. As described above, by using two antennas and switching to the one with the better reception condition,
Even under multipath fading, relatively stable communication quality can be obtained.

[0007]

The above-described conventional antenna switching device and the radio equipment using the same have the following problems. For example, in a portable wireless device such as a mobile phone terminal, it is difficult to secure a sufficient distance between both antennas from the viewpoint of miniaturization of the device, and the ground common to both antennas is very unclear for various reasons. It is stable, and therefore, as shown in the figure, the mutual coupling amount between both antennas becomes so large that it cannot be ignored. This increase in the amount of mutual coupling generally does not have a serious effect on the correlation coefficient, but on the other hand, there is a problem that the radiation characteristics of the antenna on the operating side change depending on the state of the antenna on the standby side. cause.

The antenna on the standby side is released and terminated in the antenna switching device, but due to the existence of the electrical length of the high frequency transmission line, a certain reactance value X ₀ is equal to the state in which the antenna on the standby side is loaded. it is conceivable that. That is, the loaded reactance value X ₀ changes depending on the electrical length of the high-frequency transmission line on the standby side, which changes the radiation characteristic of the antenna on the operating side. There is no problem if this change in radiation characteristics is a change in a good direction, but even if the change in a bad direction, such as a large deterioration of gain, occurs, the length of the high-frequency transmission line is changed. Currently, the change is difficult to execute because it involves the design of the entire set.

Further, the technical means for predicting these characteristic changes has not yet been developed, and therefore it is impossible to optimize the design of the length of each high frequency transmission line in advance. That is, in the present situation, there is almost no measure to be taken as a decisive factor against the characteristic change of the antenna on the operating side due to the mutual coupling. The present invention has been made to solve the above problems, and provides an antenna switching device capable of flexibly coping with characteristic changes due to mutual coupling, and an antenna switching diversity type radio configuration using the antenna switching device. It is in.

[0010]

According to another aspect of the present invention, there is provided an antenna switching device in which a first antenna is connected to a movable terminal of a first selection switch and a second antenna is connected to a second antenna.
Connected to the movable terminal of the selection switch, the first selection switch is provided with a first fixed terminal and a second fixed terminal, the second selection switch is provided with a third fixed terminal and a fourth fixed terminal,
Connect the first loading impedance between the first fixed terminal and ground, connect the second loading impedance between the third fixed terminal and ground, and connect the second and fourth fixed terminals to the output terminal. , When the first selection switch is connected to the first fixed terminal, the second selection switch is connected to the fourth fixed terminal, and when the first selection switch is connected to the second fixed terminal, The second selection switch is configured to be connected to the third fixed terminal.

According to a second aspect of the present invention, there is provided a radio device in which a circuit of the radio device is connected to an output terminal of the antenna switching device according to the first aspect.

An antenna switching device according to a third aspect of the present invention has the antenna switching device according to the first aspect, wherein the first and second loading impedances are common loading impedances.

As described above, when the antenna switching device according to the present invention is applied to an antenna switching diversity type portable radio device, it is relatively easy to change the design for the deterioration of radiation characteristics due to mutual coupling between both antennas. Can be dealt with, and a desired operation can be obtained.

[0014]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of an antenna switching device using an antenna switching device 8 according to a first embodiment of the present invention and a radio device using the antenna switching device. Similar to the conventional configuration of FIG. 3, the first antenna 1 and the second antenna 2 are spatially separated from each other. The interval is set to about 0.2 to 0.3 wavelength of the used frequency so that the correlation coefficient is extremely low spatially.

A first high-frequency transmission line 3 and a second high-frequency transmission line 4 are electrically connected to these two antennas, respectively, and received by the two antennas which are spatially separated from each other. It plays the role of collecting signals in one place. In addition, the ends of both of these high-frequency transmission lines 3 and 4 are
The input terminals 5a and 5b of the antenna switching device 8 are electrically connected to each other. In the embodiment of the present invention, the antenna switching device 8 has two first selection switches 9 and a second selection switch 9.
Selection switch 10 is provided and each movable contact 9a, 10a is connected to the input terminals 5a, 5b.

The second fixed contact 9c and the fourth fixed contact 10c are connected to the output terminal 5c, and the other first fixed contact 9b and the third fixed contact 10b have predetermined reactance values X1 and X2. Loading impedance 11a, 1
They are connected to 1b respectively. The switching operation of these two selection switches 9 and 10 is performed in conjunction with the seesaw type, and when the first selection switch 9 is pushed down to the first fixed contact 9b side, Selection switch 10
To the fourth fixed contact 10c side, or when the first selection switch 9 is set to the second fixed contact 9c side, the second selection switch 10 is set to the third fixed contact 10b side. That is, the antenna on the operating side is connected to the circuit of the wireless device, and at the same time, the antenna on the standby side is connected to the loading impedance.

By substituting the antenna switching device 8 as described above for the conventional antenna switching device 5, it is possible to deal with the characteristic change of the operating side antenna due to mutual coupling as described below. The antenna on the standby side
A certain reactance value X1 'or X2' determined by the loading impedances 11a and 11b and the electrical lengths of the high-frequency transmission lines 3 and 4 is loaded, and the radiation characteristics of the antenna on the operating side are changed by mutual coupling. Up to the point where it can be changed, it is the same as the conventional case. However, when the desired characteristic cannot be obtained due to the change in the characteristic, the conventional technique has no countermeasure, whereas in the present embodiment, the loading impedances (passive elements) 11a and 11b are changed. It is possible to change the loading reactance value relatively easily, and therefore it becomes possible to change the design optimally for the characteristic change due to mutual coupling.

FIG. 2 is a schematic diagram showing the configuration of the antenna switching device 12 of the second embodiment according to the present invention. This antenna switching device 12 uses the loading impedances 11a and 11b in the first embodiment as a common loading impedance (passive element) 13. For example, when the optimum reactance values of the respective passive elements are very close to each other, the common effect can be achieved by reducing the manufacturing cost.

[0019]

As described above, when the antenna switching device of the present invention and the wireless device using the same are applied to the portable wireless device of the antenna switching diversity system, the radiation characteristics are deteriorated due to mutual coupling between both antennas. On the other hand, it is possible to cope with the design change relatively easily, and a desired operation can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an antenna switching device and a wireless device according to a first embodiment.

FIG. 2 is a schematic diagram of an antenna switching device showing a second embodiment.

FIG. 3 is a schematic diagram of a conventional antenna switching device and a wireless device.

[Explanation of symbols]

 1 1st antenna 2 2nd antenna 3 1st high frequency transmission line 4 2nd high frequency transmission line 5 Conventional antenna switching device 5a, 5b Input terminal 5c Output terminal 5a2, 5a2 Fixed contact 5c1 Moving contact 6 Selection switch 7 Radio circuit 8 Antenna switching device of the first embodiment 9 First selection switch 9a Movable terminal of the first selection switch 9b First fixed terminal of the first selection switch 9c Second of the first selection switch Fixed terminal 10 Second selection switch 10a Movable terminal of second selection switch 10b Third fixed terminal of second selection switch 10c Fourth fixed terminal of second selection switch 11a First loading impedance (passive element ) 11b Second loading impedance (passive element) 12 Antenna switching device of the second embodiment 13 Common loading impedance (passive) Child)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hironori Ito 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (3)

[Claims] 1. A first antenna is connected to a movable terminal of a first selection switch, a second antenna is connected to a movable terminal of a second selection switch, and the first fixed switch is fixed to the first selection switch. A terminal and a second fixed terminal are provided, a third fixed terminal and a fourth fixed terminal are provided on the second selection switch, and a first loading impedance is connected between the first fixed terminal and a ground, A second loading impedance is connected between the third fixed terminal and ground, the second and fourth fixed terminals are connected to an output terminal, and the first selection switch is connected to the first fixed terminal. When the second selection switch is connected to the fourth fixed terminal, and when the first selection switch is connected to the second fixed terminal, the second selection switch is connected to the third fixed terminal. An antenna switching device that is made to be connected. 2. A radio device in which a circuit of a radio device is connected to the output terminal of the antenna switching device according to claim 1. 3. The antenna switching device according to claim 1, wherein the first and second loading impedances are common loading impedances.