JP2783071B2 - transceiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio apparatus for transmitting and receiving radio waves using a rod antenna such as a whip antenna, and more particularly to a radio apparatus in which a reduction in antenna gain of the rod antenna in a signal frequency band to be used is avoided.

[0002]

2. Description of the Related Art Conventionally, in a portable radio such as a cellular phone, a rod-shaped antenna (such as a whip antenna) having a half-wavelength antenna element length is often used for transmitting and receiving radio waves. This rod-shaped antenna can not only make the radiation pattern and the antenna gain almost equal to those of the dipole antenna, but also have a feature that the radiation pattern and the antenna gain change little even when the radio is held on the head of the human body. Have. Further, since the rod-shaped antenna can be easily accommodated in the wireless device by reducing the antenna element length, the portability of the wireless device can be improved. This rod-shaped antenna has a high radiation impedance of several hundred ohms or more.

The radio further includes a duplexer for separating a transmission signal supplied from the transmission unit to the rod antenna and a reception signal supplied from the rod antenna to the reception unit. To the feeding end of However, since the input / output end impedance of the duplexer is usually designed to be about 50Ω, it is necessary to provide an impedance matching device between the duplexer and the rod-shaped antenna in order to prevent a decrease in antenna gain in a used signal frequency band. There is.

One of the conventional impedance matching devices of this type is disclosed in Japanese Patent Application Laid-Open (JP-A-63-1760).
03, published; 1988.7.20, title of the invention; antenna device). This impedance matching device has a low-pass filter type configuration having an inductor connected in series to the transmission line and a capacitance connected in parallel to the transmission line, and the frequency of the transmission signal (hereinafter, transmission frequency)
The impedance matching between the rod-shaped antenna and the duplexer is substantially optimized at a frequency substantially intermediate between the frequency of the received signal and the frequency of the received signal (hereinafter, reception frequency).

[0005]

However, in the above-mentioned radio equipment to which the prior art is applied, a frequency band (hereinafter referred to as a matching band) in which the impedance matching between the rod antenna and the duplexer can be optimized by the impedance matching device. )
Is only about a few percent near the midpoint between the transmission frequency and the reception frequency, provided that the condition of impedance matching is VSWR 2.0 (return loss 9.6 dB) or less. Therefore, in the above-mentioned radio, when the used signal frequency band is wide or the transmission frequency and the reception frequency are largely separated, the antenna and the transmission / reception unit can be used in a desired signal frequency band even if the impedance matching device is used. Sufficient impedance matching could not be performed between the antennas, and the effective antenna gain could not be reduced except for a part of the used signal frequency band.

SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to provide a wireless device which transmits and receives radio waves by means of a rod-shaped antenna and which can avoid a decrease in antenna gain of the rod-shaped antenna in a used signal frequency band.

A second object of the present invention is to provide a radio apparatus for transmitting and receiving radio waves using a rod-shaped antenna, which has an antenna gain due to impedance mismatch at least in the frequency band of both signals even if the transmission frequency and the reception frequency are far apart. An object of the present invention is to provide a wireless device that does not cause deterioration.

[0008]

A radio apparatus according to the present invention has a rod-shaped antenna for transmitting and receiving a transmission signal and a reception signal by electromagnetic waves, receives the reception signal at an antenna terminal, and supplies the reception signal from the reception terminal to a reception section. And a duplexer that receives the transmission signal from the transmission unit at a transmission terminal and supplies the transmission signal from the antenna terminal to the power supply terminal. The rod-shaped antenna can be put in and taken out of the housing of the wireless device, and the length of the antenna element is set to approximately one wavelength corresponding to an intermediate frequency between the transmission frequency and the reception frequency.
/ 2 can be extended. In this wireless device, an impedance matching device for impedance matching between the rod antenna and the duplexer is connected between the rod antenna and the duplexer.

The impedance matching device includes a first inductor connected between a feeding end of the rod-shaped antenna and an antenna terminal of the duplexer, and a first inductor connected between the feeding end and a ground potential point. A capacitor constitutes an impedance conversion circuit, and a parallel resonance circuit comprising a second inductor and a second capacitor is provided between the antenna terminal and the ground potential point and performs parallel resonance substantially at the intermediate frequency. By properly selecting the constants of the inductor and the capacitor, the impedance matching circuit can achieve impedance matching between the antenna and the duplexer at the transmission frequency and the reception frequency, respectively. As a result, even when the transmission frequency and the reception frequency are close to each other, even when the two frequencies are largely separated, the transmission frequency of the transmission signal and the reception signal in the signal frequency band of the reception signal are different between the rod-shaped antenna and the transmission / reception duplexer. Thus, impedance matching can be ensured.
Therefore, the antenna gain of the rod-shaped antenna does not decrease in the signal frequency bands of the transmission signal and the reception signal.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention. FIG. 2 is a sectional view of this embodiment, and FIG.
(A) shows a side section, and FIG. 2 (b) shows a front section.

Referring to FIGS. 1 and 2, this portable telephone transmits a transmission signal as an electromagnetic wave and receives the electromagnetic wave as a reception signal by a rod-shaped antenna 1 such as a whip antenna. The length L of the antenna element of the antenna 1 can be changed. That is, when the radio is used, the antenna element length L is set to approximately の of the wavelength corresponding to the intermediate frequency between the transmission frequency and the reception frequency. When the radio is not used, the antenna 1 is mounted on the housing. 14
It is housed in a reduced size (see the two-dot chain line in FIG. 2) for convenient carrying. The feeding end 1a of the antenna 1 is connected to the conductive support portion 2 and held by the housing 14, and further connected to the antenna connection of the impedance matching circuit 4 via the elastic conductive connection portion 3 connected to the support portion 2. Connected to terminal 41. The power receiving terminal 46 of the matching circuit 4
It is connected to the antenna terminal 51 of the duplexer 5 for separating the transmission signal and the reception signal.

The antenna impedance when the antenna 1 is viewed from the feeding end 1a of the antenna 1 is very high, and is several hundreds Ω or more. On the other hand, the duplexer impedance when viewing the duplexer 5 from the antenna terminal 51 is generally designed to be about 50Ω. Therefore, the matching circuit 4 performs impedance matching between the antenna impedance and the duplexer impedance at the transmission frequency and the reception frequency, thereby preventing the antenna gain of the antenna 1 from being reduced.

The matching circuit 4 includes an impedance conversion circuit including an inductor 43 inserted between the antenna connection terminal 41 and the power receiving terminal 46 and a capacitor 42 connected between the antenna connection terminal 41 and the ground potential point. A parallel resonance circuit comprising an inductor 45 and a capacitor 44 connected in parallel between the terminal 46 and the ground potential point and performing parallel resonance at a frequency substantially intermediate between the transmission frequency and the reception frequency is provided. When the constants of the inductors 43 and 45 and the capacitors 42 and 44 are properly selected, the matching circuit 4 performs impedance matching between the antenna and the duplexer in the transmission signal frequency band and the reception signal frequency band, respectively. Can be. Note that even if the transmission frequency and the reception frequency are far apart, impedance matching can be achieved at each frequency,
Therefore, it is possible to prevent the antenna gain from decreasing in the signal frequency band used by the antenna 1. A method of setting the constants of the inductors 43 and 45 and the capacitors 42 and 44 of the matching circuit 4 will be described later with reference to FIG.

The duplexer 5 selects a reception signal received by the antenna terminal 51 via the antenna 1, the support unit 2, the connection unit 3, and the matching circuit 4 by the band-pass filter 53, and transmits the selected signal to the reception terminal 55. Occurs. This received signal is processed by the receiving unit 7 and further converted into a sound wave by the receiver 9. On the other hand, the voice signal from the transmitter 8 is converted into a transmission signal by the transmitter 6. The transmission signal is supplied to the transmission terminal 54 of the duplexer 5, selected by the bandpass filter 52, and supplied to the antenna terminal 51. This transmission signal is
Further, the power is supplied to the feed end 1 a of the antenna 1 via the matching circuit 4, the connection unit 3 and the support unit 2.

1 and 2 are controlled by a control unit 11 for controlling various components of the telephone, a keyboard 10 for inputting outgoing signals and the like to the control unit 11, and a control unit 11 instructed by the control unit 11. A display unit 12 for displaying an incoming signal and the like;
A battery package 13 for supplying power to various components of the telephone is included. The duplexer 5 and the transmitter 6
The receiving unit 7 and the control unit 11 are mounted on the same printed circuit board 15.

In this portable telephone, the transmission signal and the reception signal are separated in the frequency domain by the transmission / reception duplexer 5, but this signal separation may be performed by the transmission unit 6 and the reception unit 7. . In this case, the transmission signal output terminal of the transmission unit 6 and the reception signal input terminal of the reception unit 7 are connected, and this connection terminal becomes the antenna terminal 51 in the embodiment of FIG.

FIG. 3 is an enlarged plan view of the matching circuit 4 included in the block diagram of FIG.

Referring to FIG. 3, the matching circuit 4 has chip type capacitors 42 and 44 and inductors 43 and 45 formed by printed wiring on a printed circuit board 48. The matching circuit 4 further includes an antenna connection terminal 41, a power receiving terminal 46, and a ground conductor 47 serving as a ground potential point formed by printed wiring. Note that the inductors 43 and 45 can be considered almost as distributed constant circuits. It is also possible to mount the inductors 43 and 45 on the printed circuit board 48 as a lumped constant circuit. These errors in setting the inductance of the inductors 43 and 45 can be reduced by employing printed wiring. Conversely, capacitor 4
The components 2 and 44 may be constituted by distributed constant circuits if the required capacitance is small. The matching circuit 4 may be mixedly mounted on, for example, a printed circuit board 15 on which other components of the wireless device are mounted.

FIG. 4 is a Smith chart illustrating an impedance matching method between the antenna 1 and the duplexer 5 in the embodiment of FIG.

The impedance matching method of this embodiment will be described with reference to FIGS. 1 and 4. The rod-shaped antenna 1 whose impedance chart is shown in FIG.
It has an antenna element length L of 5 cm, and the frequency (center frequency) f0 at which the maximum antenna gain occurs is approximately 900 MHz. This impedance chart shows impedances Za to Zd of the broadly defined antenna circuit including the antenna 1, the support unit 2, the connection unit 3, and the matching circuit 4 from a frequency of 0.85f0 to a frequency of 1.15f0.
The transmission frequency f1 is 0.93f0, the reception frequency f2
Is 1.07f0. The duplexer impedance when viewing the duplexer 5 from the antenna terminal 51 is 50Ω.

In FIG. 4, the antenna impedance Z when the antenna 1 is viewed from the antenna connection terminal 41 of the matching device 4 is shown.
a is 250Ω−j32Ω (5-j) at the center frequency f0.
0.64). In addition,
The impedance Za includes a reactance component contributed by the support unit 2 and the connection unit 3. A susceptance component is added to the impedance Za by the capacitor 42, and a resistance of the added impedance Zb at the center frequency f0 is set to a predetermined standardized resistance Rb1. The susceptance component described above is about j0.7 at the center frequency f0, and the capacitance 42
Of about 2.5 pF. Next, a reactance component is added to the impedance Zb by the inductor 43, and the added impedance Zc is converted to a pure resistance Rb1 at the center frequency f0.
At this time, the return loss at the center frequency f0 is a3
(In FIG. 4, the return loss is about 7 dB). Further, the above-described reactance component is about j1.3 at the center frequency f0.
And the inductance of the inductor 43 is about 11.5.
nH.

Finally, a susceptance component is added to the impedance Zc by a parallel resonance circuit including a capacitor 44 and an inductor 45, and a required matching state a2 (in FIG. 4, VSWR2 or less, near FIG. 4) near the transmission frequency f1 and the reception frequency f2. Or return loss about 9.6d
B or more).

Here, in order to make the impedance Zd when the antenna 1 is viewed from the power receiving terminal 46 into the matching state a2 over the entire signal frequency band for both the transmission signal and the reception signal, the transmission frequency which is the center frequency of these signals is used. Both the f1 and the reception frequency f2 are almost in the best matching state a1 (VSWR 1.2 or less in FIG. 4, or a return loss of about 21
dB or more). In this embodiment, the susceptance value, which is the reciprocal of the impedance Zc, is different from about +0.9 and -1.5 at the transmission frequency f1 and the reception frequency f2, respectively. Therefore,
Resonant frequency fr by capacitor 44 and inductor 45
Is somewhat lower than the intermediate frequency f0 (fr （0.97
f0), the corrected susceptance values for the transmission frequency f1 and the reception frequency f2 are made different from each other, and the impedance Zd at both the frequencies f1 and f2 is set to the best matching state a1. The capacitor 44 of the above-described parallel resonance circuit has a capacitance of about 27 pF, and the inductor 45 has an inductance of about 1.2 nH.

The impedance of the capacitor 42 and the inductor 43 are adjusted so that the impedance Zc becomes the pure resistance Rb2 in the matching state a2 at the center frequency f0.
, The required matching state a2 can be obtained in the continuous transmission signal and reception signal frequency bands.

FIG. 5 is a diagram showing the impedance matching characteristics of the antenna according to the embodiment of FIG. 1 in comparison with those of the prior art.

Referring to FIG. 5, a return value A (broken line) according to the impedance chart shown in FIG. 4 for the return loss when the antenna 1 side is viewed from the power receiving terminal 46 of the matching circuit 4 is shown.
And the actual measured value B of the return loss according to this embodiment (solid line)
And a measured value C (dot-dash line) using an impedance matching device according to the prior art. This figure shows a good agreement between the calculated value A and the actually measured value B. In the figure, the matching band having a return loss of 9.6 dB or more (matching state S2) is substantially 7 centered on the center frequency f0 in the measured value C.
% (Range of Δf0), whereas the measured frequency B indicates the transmission frequency f1 = 0.93f0 and the reception frequency f2
5% or more (range of Δf1 and Δf2) at 1.07f0. The return loss at the transmission frequency f1 and the reception frequency f2 in the actually measured value C is about 5.5 dB, and the matching device 4 in FIG.
And f2 greatly improved.

FIG. 6 is a diagram showing gain characteristics corresponding to the impedance matching characteristics of FIG.

Referring to FIG. 6, the antenna gain D (dBd) of the antenna 1 corresponding to the actually measured value B of the return loss viewed from the power receiving terminal 46 of the matching circuit 4 and the antenna 1 of the antenna 1 which has been subjected to the impedance matching according to the prior art. The antenna gain E corresponding to the actually measured value C is shown. In the vicinity of the transmission frequency f1 and the reception frequency f2, the antenna gain D is improved by about 1 to 2 dB in proportion to the return loss improvement as compared with the antenna gain E.

[0030]

As described above, according to the present invention, the first inductor connected between the feeding end of the rod-shaped antenna and the antenna terminal of the transmitting / receiving section via the connecting member, and the connection between the feeding end and the ground potential point are described. A first capacitor connected between the antenna terminal and the second inductor and a second capacitor to form a parallel resonance circuit between the antenna terminal and a ground potential point; The resonance circuit resonates in parallel at a frequency substantially intermediate between the received signal and the received signal. The impedance matching circuit including the impedance conversion circuit and the parallel resonance circuit appropriately selects the constants of the first and second inductors and the first and second capacitors so that the transmission frequency and the reception frequency are different from each other. Implement impedance matching between the antenna and the transceiver. Therefore, this radio can not only broaden the matching band near the intermediate frequency but also, when the transmission frequency and the reception frequency are greatly separated, the antenna and the transmission / reception unit in the transmission signal and the reception signal respectively. Therefore, the antenna gain of the antenna is not reduced in the signal band of the transmission signal and the reception signal.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIGS. 2A and 2B are cross-sectional views of this embodiment, in which FIG. 2A shows a side cross section and FIG. 2B shows a front cross section.

FIG. 3 is an enlarged plan view of a matching circuit 4 included in the block diagram of FIG.

FIG. 4 is a Smith chart illustrating an impedance matching method between the antenna 1 and the duplexer 5 in the embodiment of FIG. 1;

5 is a diagram showing impedance matching characteristics of the antenna according to the embodiment of FIG. 1 in comparison with those of the prior art.

6 is a diagram showing gain characteristics corresponding to the impedance matching characteristics of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna 1a Feeding end 2 Support part 3 Connection part 4 Impedance matching circuit 5 Transmitter / receiver 6 Transmitter 7 Receiver 8 Receiver 9 Receiver 10 Keyboard 11 Control part 12 Display part 13 Battery package 14 Housing 15, 48 Printed circuit board 41 Antenna connection terminals 42, 44 Capacitors 43, 45 Inductor 46 Power receiving terminal 47 Ground conductor 51 Antenna terminal 52, 53 Bandpass filter 54 Transmission terminal 55 Reception terminal

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04B 1/38-1/58

Claims (12)

(57) [Claims] A transmitting unit that supplies a transmitting signal to an antenna terminal; a receiving unit that receives a receiving signal having a frequency different from the transmitting signal from the antenna terminal; and the transmitting unit, the receiving unit, and the antenna terminal. A housing means for housing, a rod-shaped antenna means which is freely housed in the housing means, and which can extend the antenna element length to approximately half the wavelength corresponding to the intermediate frequency between the transmission signal and the reception signal; The impedance between the transmitting / receiving unit impedance, which is connected between the antenna terminal and the feeding end of the rod-shaped antenna means when the transmitting means and the receiving means are viewed from the antenna terminal, and the antenna impedance when the rod-shaped antenna means is viewed from the feeding end. A wireless device comprising: impedance matching means for performing matching; wherein the impedance matching means comprises: A first inductor inserted between the power supply end and a ground potential point; a first inductor inserted between the power supply end and a ground potential point; and a first inductor inserted between the power receiving terminal and a ground potential point. And a parallel resonance circuit means including a second inductor and a second capacitor connected in parallel to each other and performing substantially parallel resonance at the intermediate frequency. 2. The wireless device according to claim 1, wherein said impedance matching means is mounted on a printed circuit board. 3. The method according to claim 2, wherein the first and second inductors are formed of a conductor pattern formed on the printed circuit board, and the first and second capacitors are chip capacitors. Radio. 4. The impedance matching means further includes an antenna connection terminal on the printed circuit board, the antenna connection terminal being a common connection point between the first inductor and the first capacitor. 3. The radio device according to claim 2, further comprising: conductive support means for holding the power supply end of the power supply terminal in the housing; and connection means for electrically connecting the support means and the antenna connection terminal. 5. The wireless device according to claim 1, wherein said impedance matching means causes the impedance matching to be maximized near the center frequency of each of the transmission signal and the reception signal. 6. The wireless device according to claim 4, wherein said impedance matching means causes the impedance matching to be maximized near the center frequency of each of the transmission signal and the reception signal. 7. A transmitting means for transmitting a transmitting signal, a receiving means for receiving a receiving signal having a frequency different from the transmitting signal, a housing means for accommodating the transmitting means and the receiving means,
Rod-shaped antenna means which can be freely taken out of the housing means and extend the length of the antenna element to approximately half the wavelength corresponding to the intermediate frequency between the transmission signal and the reception signal; and Receiving and supplying the receiving signal from the receiving terminal to the receiving means, and receiving the transmitting signal from the transmitting means to the transmitting terminal and outputting from the antenna terminal, a feeding end of the rod-shaped antenna means, and the transmitting / receiving duplexer Impedance matching means inserted between the antenna terminal of the means and the impedance matching means for performing impedance matching between the antenna impedance when viewing the rod-shaped antenna means from the feeding end and the duplexer means impedance when viewing the duplexer means from the antenna terminal. Wherein the impedance matching means is provided between the power supply end and the antenna terminal. , A first capacitor inserted between the antenna terminal and a ground potential point, and a second inductor inserted between the antenna terminal and a ground potential point and connected in parallel with each other. And a parallel resonance circuit means that includes a second inductor and a second capacitor and performs substantially parallel resonance at the intermediate frequency. 8. The wireless device according to claim 7, wherein said impedance matching means is mounted on a printed circuit board. 9. The semiconductor device according to claim 8, wherein the first and second inductors are formed of a conductor pattern formed on the printed circuit board, and the first and second capacitors are chip capacitors. Radio. 10. The impedance matching means further includes an antenna connection terminal on the printed circuit board, the antenna connection terminal being a common connection point between the first inductor and the first capacitor. 9. The wireless device according to claim 8, further comprising: conductive support means for supporting the power supply end of the power supply terminal on the housing; and connection means for electrically connecting the support means and the antenna connection terminal. 11. The radio apparatus according to claim 7, wherein said impedance matching means causes the maximum impedance matching to occur near the center frequency of the transmission signal and the reception signal. 12. The radio apparatus according to claim 10, wherein said impedance matching means causes the maximum impedance matching to occur at about the center frequency of the transmission signal and the reception signal.