JPH08172374A - Portable radio equipment - Google Patents

Abstract

PURPOSE: To obtain a diversity antenna capable of reducing the mutual coupling of two antennas without complicating circuit constitution and to attain a compact portable radio equipment having excellent portability. CONSTITUTION: The portable radio equipment is provided with a square microstrip antenna 11, a herical sleeve antenna 12, an antenna changing switch 13 connected to the two antennas 11, 12, a transmitter 15 and a receiver 16 connected to the switch 13 through a transmission/reception changing switch 14, a received power level detecting circuit 17 for detecting the power level of a received signal, and a microcomputer 18 for outputting an antenna switching signal (a) for switching a current antenna to the other one when the power level is reduced less than a previously set threshold to the switch 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable wireless device having a diversity function.

[0002]

2. Description of the Related Art In this type of portable radio device, space diversity by two antennas is effective in consideration of feasibility, operability, portability, cost and the like. As a portable wireless device having two antennas, for example, Japanese Patent Laid-Open No. 62-497.
No. 29 publication. FIG. 3 is a perspective view of a conventional portable wireless device disclosed in that publication, and FIG.
The portable wireless device 1 shown in FIG. 2 is provided with two sleeve antennas 1a and 1b on the upper surface of the housing, and the portable wireless device 2 in FIG. 1B is provided with two whip antennas 2a and 2b. The portable wireless device 3 shown in FIG. 3C has two rectangular microstrip antennas 3a and 3b mounted inside the back side of the housing.

[0003]

However, as shown in FIG.
In the conventional portable wireless device shown in (a) and (b), since the two antennas 1a and 1b (or 2a and 2b) are arranged extremely close to each other on the upper surface of the housing, mutual coupling is large. However, the impedance characteristics and directivity were easily influenced by each other, and the design was not easy. Also, it was not preferable from an aesthetic point of view.

Further, in the portable wireless device of FIG. 3C, unlike the above-described wireless devices 1 and 2, since the rectangular microstrip antennas 3a and 3b are housed inside the back side of the housing, portability is improved. And good operability,
Since the volumes of the antennas 3a and 3b are large, the allowable volume of the power supply unit and the electric circuit unit is small. Also, in the arrangement method of the rectangular microstrip antennas 3a and 3b, the mutual coupling between the two antennas is large, so that impedance characteristics and directivity are improved. The sexes were more susceptible to each other.

Conventionally, as a means for solving these problems, it has been disclosed in the above-mentioned publication (see FIG. 4), but in the portable wireless device 4, the antenna on the upper surface of the casing is a sleeve antenna 4a (or a whip). Since it is an antenna), it has a long protrusion from the upper surface of the casing and lacks portability.
Further, the rectangular microstrip antenna 4b provided inside the back side of the housing is dedicated to reception, so that a dedicated receiver is required in addition to the receiver connected to the sleeve antenna 4a, and the circuit configuration is reduced. It was complicated.

The present invention has been made to solve the above problems, and provides a diversity antenna in which the mutual coupling of two antennas is small without complicating the circuit structure, and is small and portable. The purpose is to provide a radio.

[0007]

A portable radio device according to the present invention is a helical type in which a linear antenna portion of a sleeve antenna having a sleeve portion and a linear antenna portion having the same length as the sleeve portion is formed into a helical shape. The sleeve antenna, the square microstrip antenna, the antenna changeover switch to which the helical sleeve antenna and the square microstrip antenna are connected, the receiver and transmitter connected to the antenna changeover switch, and the level of the received signal at the time of reception An antenna selection circuit that outputs an antenna switching signal for switching to the other antenna when the threshold value is less than or equal to a preset threshold value to the antenna switching switch.

In the helical sleeve antenna, only the helical antenna portion projects from the upper surface of the casing. Further, the rectangular microstrip antenna is provided inside the surface of the housing held by the user and the surface other than the upper surface.

[0009]

In the present invention, the helical sleeve antenna has a vertical polarization characteristic, and the rectangular microstrip antenna has a horizontal polarization characteristic, and it is switched to the antenna having the higher reception level of the two antennas. For example, when a radio wave is received while the antenna changeover switch is switched to the helical sleeve antenna, the received wave is input to the receiver via the antenna changeover switch. At that time, the antenna selection circuit compares the signal level of the received wave with a preset threshold value, and when the signal level exceeds the threshold value, the helical sleeve antenna continues reception and the signal level is When it becomes less than the threshold value, the antenna switching signal is output to the antenna switching switch and switched to the rectangular microstrip antenna side to continuously receive the radio wave.

Further, when only the helical antenna part of the helical sleeve antenna is projected from the upper surface of the housing, the length of the portable radio becomes shorter,
It is compact and has excellent portability. Further, since the rectangular microstrip antenna is installed at a position apart from the helical sleeve antenna and inside the surface other than the housing surface gripped by the user, mutual coupling between both antennas is extremely small. .

[0011]

FIG. 1 is a schematic block diagram of a digital mobile phone showing an embodiment of the present invention, and FIG. 2 is a perspective view showing the appearance of the mobile phone.

In the figure, reference numeral 10 is a housing of a mobile phone having a receiver 10a and a transmitter 10b on the front surface, and generally, the central portions of both side surfaces and the rear surface thereof are grip portions.
Reference numeral 11 denotes a rectangular microstrip antenna having a horizontal polarization characteristic, which is composed of a radiation conductor plate 11a, a ground conductor plate 11b, and a connection conductor plate 11c for connecting both conductor plates 11a and 11b to each other. It is provided inside the back side. It should be noted that this antenna may be arranged on either one of the side surfaces near the handset 10a, or on one of the side surfaces near the transmitter 10b.

Reference numeral 12 is a helical sleeve antenna having a vertical polarization characteristic. The linear antenna portion of the sleeve antenna (internal conductor of the feed line 12a) is formed into a helical shape (helical antenna portion). Part 1
Only 2b protrudes from the upper surface of the casing 10 and the protective cover 1
It is covered with 2d. The sleeve 12c and the helical antenna portion 12b each have a length of λ / 4, and the protective cover 12d has a length of about 20 mm.

Reference numeral 13 is an antenna changeover switch for switching the connection between the antennas 11 and 12 based on the input of the antenna changeover signal a, and 14 is a transmission / reception changeover switch, which is normally switched to the receiver 16 side. Reference numeral 15 is a transmitter, 16 is a receiver that receives the same radio frequency as the frequency transmitted by the transmitter 15, and 17 is a received power level detection circuit that detects the power level of the received wave input to the receiver 16.

Reference numeral 18 denotes a microcomputer (hereinafter referred to as "microcomputer"), which has a threshold switching level set in advance. When the power level from the received power level detecting circuit 17 exceeds the switching level. The connection state of the antenna changeover switch 13 is maintained, and when the power level becomes equal to or lower than the changeover level, the antenna changeover signal a is output to the antenna changeover switch 13 to be connected to the other antenna. The above-mentioned reception power level detection circuit 17 and its microcomputer 18 constitute an antenna switching circuit of the present invention.

When the incoming wave is received by any one of the rectangular microstrip antenna 11 and the helical sleeve antenna 12 in the portable telephone configured as described above, the received wave is the antenna changeover switch 13 and the transmission / reception changeover switch 14. Are sequentially input to the receiver 16. Then, it is demodulated by a demodulator (not shown) and converted into an audio signal. At that time, the reception power level detection circuit 17 detects the power level of the reception wave and outputs it to the microcomputer 18. The microcomputer 18 compares the preset switching level with the power level, and when the power level exceeds the switching level, the connection state of the antenna changeover switch 13 is held and the received wave is continuously input, When the power level becomes lower than the switching level, the antenna switching signal a is output to the antenna switching switch 13. At this time, when the rectangular microstrip antenna 11 is in the connected state, the antenna changeover switch 13 switches to the helical sleeve antenna 12 to receive the incoming wave, and in the opposite case, the rectangular microstrip antenna 11 is received. Switch to.

According to this embodiment, the rectangular microstrip antenna 11 and the helical sleeve antenna 12 are arranged at the above-mentioned positions so that mutual coupling between the two antennas becomes extremely small. The effect that the design is easy because it is not easily affected by is obtained. Further, the helical sleeve antenna 1
Among the two, only the helical antenna portion 12b is projected from the upper surface of the housing 10, so that the total length of the mobile phone is shorter than the conventional one, and there is an effect that it is excellent in portability. Since the antenna with the higher received power level is selected from the two antennas, the fluctuation of the received power level due to fading can be improved, and the fading on the transmitting side due to the reversibility of the radio wave transmission path of the same frequency. It is also possible to suppress the deterioration of the transmission power level due to.

[0018]

As described above, according to the present invention, by using the helical sleeve antenna and the rectangular microstrip antenna, it is possible to obtain a small diversity antenna with small mutual coupling.

Further, since only the helical antenna portion of the helical sleeve antenna is made to project from the upper surface of the housing, it is smaller in size than the conventional portable wireless device and is excellent in portability. ing.

Furthermore, since the square microstrip antenna is installed at a position apart from the helical sleeve antenna and inside the surface other than the housing surface to be gripped by the user, mutual coupling between both antennas is extremely high. The effect is that it becomes smaller and the design becomes easier.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a digital mobile phone showing an embodiment of the present invention.

FIG. 2 is a perspective view showing the appearance of a digital mobile phone.

FIG. 3 is a perspective view of a conventional portable wireless device disclosed in Japanese Patent Laid-Open No. 62-49729.

FIG. 4 is a perspective view of another conventional portable wireless device disclosed in the publication.

[Explanation of symbols]

11 square microstrip antenna, 12 helical sleeve antenna, 13 antenna selector switch,
14 transmission / reception changeover switch, 17 received power level detection circuit, 18 microcomputer.

Claims (3)

[Claims] 1. A helical sleeve antenna in which a linear antenna portion of a sleeve antenna having a sleeve portion and a linear antenna portion having the same length as the sleeve portion is helical, a rectangular microstrip antenna, and the helical antenna. The antenna changeover switch to which the sleeve antenna and the rectangular microstrip antenna are connected, the receiver and transmitter connected to the antenna changeover switch, and the level of the received signal during reception is below a preset threshold value. An antenna selection circuit that outputs an antenna switching signal for switching to the other antenna at the time, to the antenna switching switch. 2. The portable wireless device according to claim 1, wherein in the helical sleeve antenna, only a helical antenna portion is projected from an upper surface of the housing. 3. The portable wireless device according to claim 1, wherein the rectangular microstrip antenna is provided inside a surface of the housing held by a user and a surface other than the upper surface. Machine.