JPH0812970B2 - Portable wireless communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is used in a wireless communication device. The invention is UHF
Suitable for small band wireless communication devices. In particular, it is suitable for use in a portable radio paging receiver.

The present invention relates to an inductively coupled antenna and a mobile wireless communication device equipped with this antenna.

[Conventional technology]

As shown in the main structure in Fig. 7, the conventional UHF band (practically 900 MHz is used in which the antenna is mounted inside the housing.
The portable radio paging receiver of the band) has a structure in which a roux antenna having a conductor formed in a loop is mounted on a circuit board on which a communication circuit is formed.

[Problems to be solved by the invention]

This loop antenna is advantageous as a structure that can be easily mounted inside the housing, but as is known from the fact that the loop antenna is used for detection of a radio wave arrival method, its antenna gain has a remarkable directional characteristic. Therefore, in consideration of the condition that the user of the portable radio paging receiver normally wears and uses, the device is mounted in the direction in which the antenna gain is maximized in the normal use condition with respect to the vertically polarized transmission wave. (See Fig. 8 (a)) The user does not always hold the device in the desired direction, but happens to rotate the device 90 ° from the direction having the maximum sensitivity to the arrival direction of the radio wave. If held (see FIG. 8 (b)), there is a drawback that the signal reception sensitivity becomes extremely small.

FIG. 9 shows an example of conventional antenna characteristics in free space.

Regarding the sensitivity of the paging receiver at a frequency of 900 MHz, the solid line in Fig. 9 shows the antenna directivity on the horizontal plane in the state corresponding to Fig. 8 (a), and the broken line in Fig. 8 (b). The antenna directivity of the horizontal plane in a corresponding state is shown. The values of the broken line with respect to the solid line are deteriorated in characteristics in all directions, and the reception sensitivity becomes extremely small.

On the other hand, a loop antenna is used as a first element, and an elongated second element is provided along a straight line orthogonal to the center of the loop of the plane formed by this loop antenna, and an inductively coupled antenna that changes the directional characteristics of the loop antenna in various ways A technique is conceivable, but if this technique is applied to the above-mentioned conventional technique, the number of elements to be mounted inside the casing increases, and it becomes impossible to form the casing itself in a small size.

The present invention is to improve this, and without diminishing the advantage that the loop antenna is advantageous in mounting, substantially without increasing the elements to be mounted inside the housing, and diversifying the directional characteristics of the antenna. It is an object of the present invention to provide a device capable of

[Means for meeting problems]

To achieve the above object, a portable wireless communication device according to the present invention includes a first conductor formed in a loop shape and connected to a radio circuit via a resonance matching circuit, and a bottom outer surface of a negative electrode cylinder of a dry battery. And a second conductor that approximates the electric length in the longitudinal direction of the dry battery to an odd multiple of a quarter wavelength of the used frequency, It is characterized in that the second conductor is arranged substantially orthogonal to the plane forming the first conductor loop, whereby the first and second conductors are electromagnetically coupled.

In addition, it is preferable to use a dry battery as an operating power source of the radio circuit.

[Action]

The negative electrode of the dry battery that supplies power to the communication circuit is an elongated metal cylinder, but the length is constant according to the standard.
The coil spring that contacts the outside of the bottom of the metal cylinder and connects the negative potential to the communication circuit can be set to be variable to some extent.
That is, it is possible to set the total length of the metal cylinder of the negative electrode and the coil spring to a quarter or an odd multiple of the wavelength of the used radio wave. Moreover, since the negative electrode of the dry battery is connected to the common potential (ground potential) of the communication circuit, there is no problem in using this as the inductive coupling element of the antenna.

Therefore, by arranging the coil spring for the dry battery and its negative electrode along a straight line that is substantially orthogonal to the plane formed by the loop and passes through substantially the center of the loop with respect to the loop-shaped first conductor, Can be used as a second conductor as an inductive coupling element for the first conductor.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a paging receiver of a portable wireless communication device according to an embodiment of the present invention.

In the figure, a loop antenna 3 and a receiver for inputting high frequency power induced by the loop antenna 3
62, a decoder 63 for inputting a demodulated wave that is amplified, frequency-converted, demodulated and waveform-shaped by the receiver 62, and an individual number given to each paging receiver from this decoder 63, and matches. In this case, the communication line including the driver 64 that causes the speaker 65 to generate an alarm sound.

The power source of this device is a dry battery 4, a capacitor 68 is connected to the positive terminal, and a receiver is connected by a power line 69.
62, the decoder 63, the driver 64, etc., and the negative electrode side is connected to the common potential of the circuit via the coil spring 6 and the negative electrode terminal 7.

FIG. 2 is a detailed view of a portion indicated by a chain double-dashed line II shown in FIG. In FIG. 2, the high frequency power induced by the loop antenna 3 is sent to the high frequency amplification transistor 73 through the resonance matching circuit 8 including the variable capacitor 70 and the capacitor 71 and amplified. The resistor 75 and the capacitor 76 are for power supply decoupling, the resistor 72 is for biasing the high frequency amplification transistor 73, and the pattern inductance 74 is a collector load. The dry battery 4 and the coil spring 6 form a second conductor of the antenna. The connection between the coil spring 6 and the ground pattern is not cut, and the impedance of the ground pattern and the open end of the coil spring 6 is measured.
The values are as shown in the figure. Here, even if the capacitor 68 and the power supply line 69, which are circuits of the positive terminal of the dry battery 4, are removed, that is, even if the positive terminal is opened, this value does not change.

This impedance is dominated by the negative electrode terminal 7 of the dry battery 4 and the coil spring 6, and is not affected by the circuit on the positive electrode terminal side. By arranging the coil spring 6 and the loop antenna 3 so as to be inductively coupled, the high frequency power induced by the dry battery 4 and the coil spring 6 is supplied from the loop antenna 3 to the high frequency amplification transistor 73. The electric power induced by each antenna is supplied to the high frequency amplification transistor 73, and even when the induced electric power of the loop antenna 3 itself becomes small, the second conductor composed of the dry battery 4 and the coil spring 6 is used. Of the loop antenna 3 is arranged so as to be orthogonal to the plane forming the loop antenna 3, and the high frequency power supplied to the high frequency amplification transistor 73 is impaired by the power from the second conductor of the antenna. Never.

FIG. 3 is a perspective view of a concrete example of an embodiment of the present invention according to the block diagram. In this figure, the housing 1 is shown by a chain double-dashed line, and the communication circuit 2 including parts is shown by a broken line for the sake of easy description.

In this configuration example, the loop antenna 3, which is the first conductor of the antenna, and the dry battery 4, which is used as the power source of this wireless device, are connected to the communication circuit 2 mounted on the printed wiring board 5 via the conductors 3a and 4a, respectively. are doing.

Here, the feature of the present invention is that the loop antenna 3 that is the first conductor is arranged along a straight line that is substantially orthogonal to the plane that forms the loop antenna 3 and that the electrical length in the longitudinal direction is equal to 4 of the used frequency. As an elongated second conductor approximating an odd multiple of one-half wavelength, it contacts the negative electrode cylinder of the outer casing of the dry battery 4 and the bottom outer surface of this cylinder, and communicates the negative potential of the dry battery via the conductor 4a. The purpose is to utilize the coil spring 6 provided in the negative terminal 7 of the dry battery that leads to the common potential in the circuit 2. At this time, the length of the negative electrode cylinder of the dry battery 4 and the coil spring 6
Has a length such that the sum of the electric length and the electric length becomes a quarter wavelength of the used frequency. One end of the negative electrode terminal 7 is in contact with the negative electrode terminal 7 of the dry battery 4, and the other end is connected to the ground pattern 2a of the printed wiring board 5 on which the communication circuit 2 is mounted. Therefore, a combination of the dry battery 4, the coil spring 6 and the ground pattern 2a of the printed wiring board 5 constitutes a base loading whip antenna. Further, the coil spring 6 is a conductor
4a and the conductor 3a of the loop antenna 3 are arranged at positions where they are inductively coupled to each other, and the dry battery 4 is arranged so that its longitudinal direction is orthogonal to the opening surface of the loop antenna 3.

FIG. 4 is an explanatory diagram of directivity with respect to a radio wave arrival direction (arrow A) according to the present embodiment. As shown in FIG. 4 (a), when the loop antenna 3 receives in the state where the loop antenna 3 is orthogonal to the arrival direction A of the radio wave, it has the maximum sensitivity as in the conventional example. In FIG. 4 (b), the loop antenna 3 is received in a state of being rotated by 90 ° with respect to the arrival direction A of the radio wave. In this case, the received power obtained by the whip antenna composed of the dry battery 4, the coil spring 6 and the ground pattern 2a of the printed wiring board 5 is supplied to the loop antenna 3 which is inductively coupled to the coil spring 6 and further to the high frequency circuit. Supplied. Sixth
An example of the characteristics of the antenna of this embodiment in free space is shown in the figure. This example shows the sensitivity of the paging receiver at a frequency of 900 MHz, the solid line shows the antenna directivity in the horizontal plane in the state shown in Fig. 4 (a), and the broken line shows Fig. 4 (b).
Shows the antenna directivity on the horizontal plane in the state corresponding to. It is apparent that the effect of the second conductor by the dry battery and the coil spring has significantly improved the characteristics as compared with the broken line in FIG. 9 which is a conventional example. That is, comparing the antenna gains at the positions of the arrows A shown in FIGS. 6 and 9, when the used band is 900 MHz, the conventional example (see the broken line in FIG. 9) has a half-wave dipole ratio of −30 dB. ,
In the actual measurement by the above-mentioned embodiment (see the broken line in FIG. 6), -10 dB
And a significant improvement of 20 dB is possible.

The wavelength of radio waves in the 900 MHz band used is about 33.3 cm, and a quarter of it is about 8.3 cm. The length of the negative electrode tube of the dry battery used in the portable radio paging receiver is about 4.2 cm. Therefore, use a coil spring with an effective length of about 4 cm.
Since one end of this coil spring supports the outer surface of the bottom of the negative electrode cylinder of the dry battery, the length of this portion does not become an effective electrical length. In addition, the coil diameter other than this portion should be as large as possible to prevent the generation of inductance.

The portable wireless communication device is provided with the circuit of the embodiment described above and the antenna, and using the dry battery as the operating power source of the communication circuit. The mobile radio communication device is implemented in particular as a mobile radio paging receiver.

〔The invention's effect〕

As described above, according to the present invention, even when the gain is reduced due to the directivity of only the loop antenna as the first conductor, the negative electrode cylinder length and the coil spring length of the dry battery are used as the second conductor as the second conductor. The inductive coupling has the effect of significantly improving the gain of the antenna.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention. FIG. 2 is a circuit diagram of the same embodiment. FIG. 3 is a perspective view of the same embodiment. FIG. 4 is an illustration of directivity of the same embodiment. FIG. 5 is an impedance characteristic diagram of the second dynamic state of the same embodiment. FIG. 6 is an antenna characteristic diagram of the same embodiment. FIG. 7 is a perspective view of a conventional example. FIG. 8 is an explanatory view of directivity of a conventional example. FIG. 9 is a conventional antenna characteristic diagram. 1 ... Housing, 2 ... Communication circuit, 2a ... Ground pattern, 3
...... Loop antenna that is the first conductor, 3a, 4a …… Conductor,
4 ... Dry battery, 5 ... Printed wiring board, 6 ... Coil spring as second conductor, 7 ... Negative terminal, 8 ... Resonance matching circuit,
62 …… Receiver, 63 …… Decoder, 64 …… Driver, 65
…… Speaker, 68 …… Capacitor, 69 …… Power line,
70 ... Variable capacitors, 71,76 ... Capacitors, 72,75
...... Resistor, 73 …… High frequency amplification transistor, 74 …… Pattern inductance, A …… Arrow indicating the direction of arrival of radio waves.

Claims (2)

[Claims] 1. A first conductor, which is formed in a loop shape and is connected to a radio circuit via a resonance matching circuit, and a negative potential of the dry cell, which is connected to the outer surface of the bottom of the negative electrode cylinder of the dry cell. A second conductor that approximates the electric length in the longitudinal direction of the coil spring that leads to the common potential of the dry battery to an odd multiple of a quarter wavelength of the frequency used, and the second conductor includes the first conductor. A portable radio communication device, wherein the first and second conductors are electromagnetically coupled by being arranged substantially orthogonal to a plane forming a loop of the conductor. 2. The portable wireless communication device according to claim 1, wherein the dry battery serves as an operating power source of the wireless circuit.