JPH08154012A - Portable radio - Google Patents

Abstract

(57) [Summary] [Purpose] An object of the present invention is to provide a portable wireless device which is not easily affected by the human body and which can transmit and receive radio waves in a wide frequency band. [Structure] Transmission circuit 16, reception circuit 17 and switching circuit 1
8, a loop antenna 11 electrically connected to the switching circuit 18, and a first switching means 20 provided between the terminal end 19 of the loop antenna 11 and the surface of the body 12 serving as the ground. The first switching means 20 is configured to select either the first capacitor 21 or the second capacitor 22 having a different electrostatic capacity by the changeover switch 23 according to the signal from the switching circuit 18.

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 that communicates by transmitting and receiving radio waves.

[0002]

2. Description of the Related Art In recent years, an antenna having a length of about ¼ wavelength of its used frequency has been used in a portable wireless device. A portable wireless device equipped with such an antenna will be described below.

FIG. 3 is a partial perspective view of a conventional portable wireless device, and FIG. 3 is a composite view in which a perspective view, a circuit diagram and a block diagram are mixed. In FIG. 3, 1 is an antenna having a length that is an odd multiple of about 1/4 of the used frequency, and 2 is a transmission circuit 6, a reception circuit 7, and a switching circuit 8 for switching between the transmission circuit 6 and the reception circuit 7. Body 3, 3 is an input / output terminal of the antenna 1, 4 is a central conductor connected to the input / output terminal 3, 4
Is a ground grounded to the main body 2. The main body 2 is composed of a metal shield case.

The operation of the portable terminal having the above structure will be described below. As shown in FIG. 3, when transmitting a radio wave from the antenna 1, the transmission circuit 6
The transmission signal output from the input terminal 3 is input from the input / output terminal 3 via the switching circuit 8 and the center conductor 4, and is transmitted from the antenna 1 as a radio wave. When receiving, the antenna 1 receives a radio wave, and the reception signal output from the input / output terminal 3 is processed by the reception circuit 7 via the center conductor 4 and the switching circuit 8.

Further, as the antenna 1, not only the antenna having the length of about 1/4 wavelength of the used frequency as described above, but also the loop antenna having the shape of a triangle or a quadrangle has been used.

[0006]

However, in the above-mentioned conventional structure, the main body 2 works as a grounding body of the antenna 1, but the antenna unit 1 uses an antenna having a length of about ¼ wavelength of the operating frequency. In this case, if the frequency used is 150 MHz in the VHF band and the wavelength is 2 m, the quarter wavelength is 50 cm, so the antenna 1 needs to have a length of about 50 cm. However, in many cases, the main body 2 of the portable wireless device has a total length of 20 cm or less from the viewpoint of portability. In such a portable wireless device, the total length of the main body 2 is too small for the length of the wavelength, and the antenna 1 It cannot fully serve as a grounding body. For this reason,
If the user holds the main body 2 by hand during communication, a current will flow through the user's hand, causing a decrease in antenna gain and deterioration of the antenna VSWR (voltage standing wave ratio). In particular, there is a problem that it leads to deterioration of communication performance in long distance communication.

If a loop antenna is used as the antenna 1 instead of an antenna having a length of about 1/4 wavelength of the used frequency, the influence of the human body can be prevented, but a 1/4 wavelength used for a portable radio device is used. Since the antenna and the loop antenna are relatively simple antennas, the usable frequency band is narrow, and there is a problem that the communication performance deteriorates when the transmission frequency and the reception frequency are different.

The present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a portable wireless device which is hardly affected by the human body and which can transmit and receive radio waves in a wide frequency band.

[0009]

In order to achieve this object, the present invention provides an internal circuit for communication, a main body having a conductor portion on its surface, and one end electrically connected to the internal circuit in the main body. And a first switching unit that is connected to the terminal end of the loop antenna and is connected to the surface of the main body that serves as a ground. The first switching unit has capacitances having different values. At the same time, one capacitor is selected from a plurality of capacitors whose electrostatic capacities are set in advance so that the loop antenna is tuned to a predetermined frequency.

Further, the internal circuit in the main body is provided with a transmitting circuit, a receiving circuit, and a switching circuit for switching between the transmitting circuit and the receiving circuit, and the plurality of capacitors connected to the first switching means have a transmitting frequency. The electrostatic capacitance is set in advance so that the loop antenna is tuned to each of the receiving frequency and the receiving frequency, and the first switching means is configured to select the capacitor according to the signal indicating the time of transmission or reception from the switching circuit.

An internal circuit for communication, a main body having a conductor portion on the surface, a loop antenna having one end electrically connected to the internal circuit in the main body, and a terminal portion of the loop antenna, and a ground And a second switching means connected to the surface of the main body, the second switching means having different line lengths, and the line length is set in advance so that the loop antenna is tuned to a predetermined frequency. In addition, one transmission line is selected from a plurality of transmission lines.

Further, the internal circuit in the main body is provided with a transmitting circuit, a receiving circuit, and a switching circuit for switching between the transmitting circuit and the receiving circuit, and the plurality of transmission lines connected to the second switching means are transmitting circuits. The route length is set in advance so that the loop antenna tunes to each frequency and reception frequency,
The second switching means is configured to select the transmission line according to a signal indicating the time of transmission or reception from the switching circuit.

An internal circuit for communication, a main body having a conductor portion on its surface, a loop antenna having one end electrically connected to the internal circuit in the main body, and a plurality of capacitors having different capacitances. And a second switching means for selecting one transmission line from a plurality of transmission lines having mutually different line lengths.
And the first switching means and the second switching means are arranged in series between the terminal end of the loop antenna and the surface of the main body.

Further, the first and second switching means respectively perform switching by a signal from the internal circuit in the main body, and one of the switching means and the internal circuit in the main body is connected to the other. The configuration is such that control means for controlling the switching is performed in consideration of the selection result of the switching means.

[0015]

With this configuration, in the first switching means provided between the terminal end portion of the loop antenna and the surface of the main body and having a plurality of capacitors having different electrostatic capacities, one capacitor is selected when performing communication. To do.

Further, the capacitances of the plurality of capacitors are set in advance so that the loop antenna is tuned to each of the transmission frequency and the reception frequency, and the preset capacitors are selected at the time of transmission or reception.

In the second switching means provided between the terminal end of the loop antenna and the surface of the main body and provided with a plurality of transmission lines having different line lengths, one transmission line is selected when performing communication.

Further, the line lengths of the plurality of transmission lines are set in advance so that the loop antenna is tuned to each of the transmission frequency and the reception frequency, and the transmission line set in advance is selected at the time of transmission or reception.

The first switching means and the second switching means are arranged in series between the terminal end of the loop antenna and the surface of the main body, and one capacitor and one transmission line are connected to each other for communication. select.

Further, a control means is provided between any one of the switching means and the internal circuit in the main body, and the selection is made by this control means in consideration of the selection result of the other switching means.

[0021]

【Example】

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a partial sectional view of a portable radio device according to the first embodiment of the present invention, which is a composite view in which a perspective view, a circuit diagram and a block diagram are mixed. In FIG.
Reference numeral 11 is a loop antenna, 12 is a main body of a portable wireless device which is a metal shield case, 13 is an input / output terminal of the loop antenna 11, 14 is a central conductor connected to the input / output terminal 13,
Reference numeral 15 is a ground that is grounded to the main body 12. Reference numeral 16 is a transmission circuit that outputs a transmission signal, 17 is a reception circuit that inputs a reception signal, and 18 is a switching circuit that switches between transmission and reception. Reference numeral 20 denotes a first switching unit provided at the terminal end portion 19 of the loop antenna 11, which is a first switching unit having a different capacitance.
It has a condenser 21 and a second condenser 22, and also has a changeover switch 23 for switching between the first condenser 21 and the second condenser 22. Reference numeral 24 is a control signal line connecting the first switching means 20 and the switching circuit 18 of the main body 12. The first control means 20 is connected to one end 19 of the loop antenna 11, and the main body 12
Is grounded to the surface.

The operation of the portable wireless device configured as described above will be described below. However, it is assumed that the portable wireless device described above uses different frequencies during transmission and during reception.

As shown in FIG. 1, the length of the loop antenna 11 is L, and the capacitances of the capacitors 21 and 22 are C1 and C2, respectively. Here, the loop antenna 11
L, the capacitance C1 of the capacitor 21 is set in advance so that the loop antenna 11 is tuned to the transmission frequency, and the capacitance C2 of the capacitor 22 is set in consideration of the length L of the loop antenna 11 in advance. Set to tune with the receive frequency. In addition, the transmission circuit 16 and the reception circuit 17
Are connected to the loop antenna 11 via the switching circuit 18.

First, when transmitting from the portable wireless device, the user sets an external changeover switch (not shown) provided on the surface of the main body 12 on the transmitting side. This external changeover switch (not shown) is connected to the changeover circuit 18, and the changeover circuit 18 sends a signal indicating that the transmission is in progress to the first changeover means 20 via the control signal line 24. First switching means 2
0 receives this signal and sets the changeover switch 23 to the first condenser 21 side. As a result, the loop antenna 11 is tuned to the transmission frequency. At this time, when a high-frequency transmission signal is output from the transmission circuit 16, the transmission signal is input to the input / output terminal 13 via the switching circuit 18, the central conductor 14, and is transmitted as a radio wave from the loop antenna 11.

Next, when receiving by the portable wireless device, the main body 1
2 When the user switches an external changeover switch (not shown) provided outside to the receiving side, the changeover circuit 18 sends a signal indicating the time of reception to the first switching means 20 via the control signal line 24. send. When the first switching means 20 receives this signal, it switches the reception changeover switch 23 to the second condenser 22 side. As a result, the loop antenna 11 is tuned to the reception frequency. At this time, loop antenna 1
1 receives a radio wave, and the reception signal output from the input / output terminal 13 is received by the reception circuit 17 via the central conductor 14 and the switching circuit 18 and processed.

In the present embodiment, the number of capacitors that can be selected by the first switching means 20 is two, but it may be three or more.

As described above, in the present embodiment, the first end portions 19 of the loop antenna 11 each having a capacitance set in advance so as to be tuned to the frequency at the time of transmission or reception.
First with a condenser 21 and a second condenser 22
When the switching means 20 is provided and the switching between the first condenser 21 and the second condenser 22 is performed by the changeover switch 23 in accordance with the case of transmission and the case of reception, when the used frequency is different between transmission and reception. However, the loop antenna 11 can be tuned to each of the transmission frequency and the reception frequency.

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

FIG. 2 is a partial cross-sectional view of a portable radio device according to the second embodiment of the present invention, which is a composite view in which a perspective view, a circuit diagram and a block diagram are mixed. In FIG.
Reference numeral 31 is a first transmission line, 32 is a second transmission line, and
The transmission line 31 and the second transmission line 32 have different line lengths. 33 is a second switching means, and the first transmission path 31
And a changeover switch 34 for switching between the second transmission path 32 and the second transmission path 32. Reference numeral 35 is a control circuit, which is the second switching means 33.
Is provided in the middle of a control signal line 36 that connects the switch circuit 18 to the switch circuit 18. The same parts as those in the first embodiment are designated by the same reference numerals. Further, similarly to the first embodiment, the portable wireless device of this embodiment is also provided with an external changeover switch (not shown) which is connected to the changeover circuit 18 and allows the user to switch between transmission and reception. .

The configuration of this embodiment is different from that of the first embodiment in that the first switching means 20 is connected in series with the second switching means 33, and the capacitor selected in the first switching means 20 and the second switching means 33 are connected in series. Since the loop antenna 11 is tuned to the frequency used by the connection with the transmission line selected by the 2 switching means 33, the number of patterns to be selected is increased so that communication can be performed in a wider frequency band than in the first embodiment. It is the point configured in.

The operation of the portable wireless device configured as described above will be described below. However, it is assumed that the portable wireless device described above uses different frequencies for transmission and reception.

As shown in FIG. 2, the terminal end 19 of the loop antenna 11 has a first capacitor 21, a second capacitor 22 and a changeover switch 23 for switching those capacitors, as in the first embodiment. The first switching means is connected. The first switching means 20 has a second switching means 33.
And the changeover switch 34 of the second changeover means 33 is
The first transmission line 31 and the second transmission line 32 are switched. In addition, the first transmission line 31 and the second transmission line 32
Are respectively grounded to the ground 15 (or the main body 12). The first transmission line 31 and the second transmission line 32
A strip substrate, a copper wire, or the like provided on the substrate is conceivable, and its shape may be a crank shape or a zigzag shape.

Here, the length of the loop antenna 11 is L, the capacitances of the first capacitor 21 and the second capacitor 22 are C1 and C2, and the lengths of the first transmission line 31 and the second transmission line 32 are L1 and L2. In such a case, considering the length L of the loop antenna 11, the capacitance C1 of the first capacitor 21 and the length L1 of the first transmission line 31 are set in advance so as to tune with the frequency at the time of transmission. In addition, the capacitance C2 of the second capacitor 22 and the second capacitor 22
The length L2 of the transmission line 32 is preset.

First, when transmitting with a portable radio, the user sets an external changeover switch (not shown) on the transmitting side. The switching circuit 18 sends a signal indicating the time of transmission to the first switching means 20 via the control signal line 24, and also sends the signal to the second switching means 33 via the control signal line 36. Is sent. Here, the first changeover means 20 changes the changeover switch 23 to the first condenser 21, and the second changeover means 33 changes the changeover switch 34 to the first transmission line 31.
Set each to. As a result, the loop antenna 11
Will tune to the transmit frequency. At this time, the high-frequency transmission signal output from the transmission circuit 16 is the switching circuit 1
8, input to the input / output terminal 13 via the central conductor 14,
It is transmitted as a radio wave from the loop antenna 11.

Next, when receiving by the portable radio, the user switches the external changeover switch (not shown) to the receiving side. The switching circuit 18 is connected to the first switching means 20 via the control signal line 24 and the second switching means 33 via the control signal line 36.
Tell each of the reception time. Here, the first changeover means 20 changes the changeover switch 23 to the second condenser 22.
Then, the second switching means 33 switches the changeover switch 34 to the second transmission line 32, respectively. As a result, the loop antenna 11 tunes to the reception frequency. At this time, the loop antenna 11 receives a radio wave, and the reception signal output from the input / output terminal 13 is received by the reception circuit 17 via the central conductor 14 and the switching circuit 18 and processed.

The number of capacitors in the first switching means 20 and the number of transmission lines in the second switching means may be further increased to widen the usable frequency range by a large number of combinations of capacitors and transmission paths.

Further, in the above-mentioned embodiment, the first means 20 and the second switching means 33 are uniquely selected so that the loop antenna is tuned to the predetermined transmission frequency and reception frequency. In consideration of the selection result of the first switching means 20, the second antenna is tuned so that the loop antenna 11 is tuned to a predetermined frequency by the combination of the capacitor of the first switching means 20 and the transmission line of the second switching means 33.
When the transmission line is selected by the control unit 33, it may be considered that the second control unit 33 is controlled by the control circuit 35.

As described above, in this embodiment, the terminal portion 19 of the loop antenna 11 is provided with the first switching means 20 having the first capacitor 21 and the second capacitor 22, and the first switching means 20 is provided with the first switching means 20. Connect the first transmission line 3
By providing the second switching means 33 including the first and second transmission lines 32, the first switching means 20 and the second switching means 33 are provided.
Since the loop antenna 11 is tuned to the used frequency by selecting a capacitor and a transmission line for each, wireless communication can be performed in a wider frequency band.

It goes without saying that the second switching means 33 may be used alone like the first switching means 20 in the first embodiment.

[0041]

As described above, according to the present invention, the first switching means provided with a plurality of capacitors having different electrostatic capacities between the terminal end portion of the loop antenna and the surface of the main body, or a plurality of different line lengths are provided. Since the second switching means provided with the transmission line is provided and the capacitor or the transmission line can be selected according to the frequency used and the loop antenna can be tuned to the frequency used, the loop antenna can be used in a small portable radio device. Even in the case where there is a situation, it is possible to realize an excellent portable wireless device that is not easily affected by the human body during communication and has a high antenna gain.

Further, a first switching means having a plurality of capacitors and a second switching means having a plurality of transmission lines are provided between the terminal end of the loop antenna and the surface of the main body.
Since the loop antenna can be tuned to the operating frequency by selecting the capacitor and the transmission line in the first switching means and the second switching means, respectively, which are arranged in series, the loop antenna can be tuned to the small portable wireless device. Even when using an antenna, it is not easily affected by the human body,
It is possible to realize an excellent portable wireless device having a higher antenna gain.

[Brief description of drawings]

FIG. 1 is a partial sectional view of a portable wireless device according to a first embodiment of the present invention.

FIG. 2 is a partial sectional view of a portable wireless device according to a second embodiment of the present invention.

FIG. 3 is a partial sectional view of a conventional mobile terminal.

[Explanation of symbols]

 11 Loop Antenna 12 Main Body 16 Transmitter Circuit 17 Receiver Circuit 18 Switching Circuit 20 First Switching Means (First Switching Means) 21 First Capacitor 22 Second Capacitor 23, 34 Changeover Switch 24, 36 Control Signal Line 31 First Transmission Line 32 second transmission line 33 second switching means (second switching means) 35 control circuit (control means)

Claims (6)

[Claims] 1. An internal circuit for communication, a main body having a conductor portion on its surface, a loop antenna having one end electrically connected to the internal circuit in the main body, and a terminal part of the loop antenna. And a first switching means connected to the surface of the main body serving as a ground, the first switching means having capacitances of different values, and the loop antenna having a predetermined frequency in advance. A portable wireless device, wherein one capacitor is selected from a plurality of capacitors whose electrostatic capacities are set so as to synchronize with each other. 2. The internal circuit in the main body comprises a transmitting circuit, a receiving circuit, and a switching circuit for switching between the transmitting circuit and the receiving circuit, and a plurality of switching circuits connected to the first switching means. The capacitor has a capacitance set in advance so that the loop antenna is tuned to each of the transmission frequency and the reception frequency, and the first switching means uses the signal from the switching circuit to indicate the transmission time or the reception time. 2. The portable wireless device according to claim 1, wherein the selection is performed. 3. An internal circuit for communication, a main body having a conductor portion on its surface, a loop antenna having one end electrically connected to the internal circuit in the main body, and a terminal portion of the loop antenna. And a second switching means connected to the surface of the main body, which serves as a ground, and the second switching means have line lengths different from each other, and
A portable wireless device, wherein one transmission line is selected from a plurality of transmission lines whose line lengths are set in advance so that the loop antenna is tuned to a predetermined frequency. 4. The internal circuit in the main body comprises a transmission circuit, a reception circuit, and a switching circuit for switching between the transmission circuit and the reception circuit, and a plurality of circuits connected to the second switching means. The line length of the transmission line is set in advance so that the loop antenna is tuned to each of the transmission frequency and the reception frequency, and the second switching means transmits the signal from the switching circuit indicating the time of transmission or reception. The portable wireless device according to claim 3, wherein a line is selected. 5. An internal circuit for communication, a main body having a conductor portion on its surface, a loop antenna whose one end is electrically connected to the internal circuit in the main body, and electrostatic capacitances having mutually different values. The first switching means is provided with a first switching means for selecting one capacitor from the plurality of capacitors included therein and a second switching means for selecting one transmission line from a plurality of transmission lines having mutually different line lengths. The portable wireless device, wherein the means and the second switching means are arranged in series between the terminal portion of the loop antenna and the surface of the main body. 6. The first and second switching means perform switching by a signal from the internal circuit in the main body, and either one of the switching means and the internal circuit in the main body is switched. 6. The portable wireless device according to claim 5, wherein control means for controlling so as to perform switching in consideration of the selection result of the other switching means is provided between them.