JPH06314982A - Antenna - Google Patents

Abstract

PURPOSE:To provide the antenna used for a broad range frequency band. CONSTITUTION:The antenna is an antenna for a radio communication equipment provided with an antenna tuned to a frequency in use and a PLL circuit having a voltage controlled oscillator and operated by plural frequencies and a tuning circuit is formed by an antenna element 3, a DC block capacitor 4 connecting to a feeding section of the antenna element 3 and a varactor diode 2 connected between one terminal of the antenna element 3 and the DC block capacitor 4, a connecting point between the varactor diode 2 and the DC block capacitor 4 is connected to an antenna ground via a high frequency choke coil 5 and a frequency control voltage from the voltage controlled oscillator 7 is superimposed on a signal of the feeding section and the tuning circuit is tuned to the operating frequency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna of a wireless communication device which is equipped with an antenna tuned to a frequency used and a PLL circuit having a voltage controlled oscillator and which operates at a plurality of frequencies.

[0002]

2. Description of the Related Art Conventionally, an electronic switching antenna has been proposed. For example, as shown in FIG. 3, a diode 21 is connected to a predetermined portion of the antenna element 20, a capacitor 22 is connected between the diode 21 and a power feeding portion of the antenna element 20, and a connecting portion between the diode 21 and the capacitor 22 is a resistor. Connect to the antenna ground via 23,
A switching voltage of the diode 21 is applied to the power feeding portion of the antenna 20 through the high frequency choke coil 24, and the diode 21 is turned on / off based on the switching voltage to set the switching voltage to 1
There is a book antenna which is electronically switched to tune to two different frequencies (Japanese Patent Application No. 4-8517).
issue).

[0003]

In this case, one antenna is designed to have as wide a band as possible, but it is difficult to completely cover a wide frequency range. As a result, there is a problem that the performance deteriorates above and below the center frequency. Further, in order to solve this, a plurality of antennas having different tuning frequencies are provided, and each antenna is replaced and used.

An object of the present invention is to provide an antenna that can be used in a wide range of frequency bands.

[0005]

SUMMARY OF THE INVENTION An antenna of the present invention is an antenna of a radio communication device which operates at a plurality of frequencies and includes a PLL circuit having an antenna tuned to a frequency to be used and a voltage controlled oscillator. , A DC blocking capacitor connected to the power feeding portion of the antenna element, and a variable capacitance diode connected between a predetermined portion of the antenna element and the DC blocking capacitor, a variable capacitance diode and a DC blocking capacitor. Is connected to the antenna ground through either a high frequency choke coil or a resistor, and the frequency control voltage of the voltage controlled oscillator is superposed on the power feeding unit to tune to the frequency used. .

[0006]

In the antenna of the present invention, the capacitive reactance of the variable diode is changed by the frequency control voltage of the voltage controlled oscillator superimposed on the feeding portion of the antenna element,
The capacitive reactance and the inductive reactance of the antenna element tune the operating frequency of the wireless communication device, and tune to a wide band frequency.

[0007]

EXAMPLES The present invention will be described below with reference to examples. Figure 1
FIG. 3 is a block diagram showing the configuration of an embodiment of the present invention.

The antenna 1 according to this embodiment has an antenna element 3, a DC blocking capacitor 4 connected to a feeding portion of the antenna element 3, a cathode connected to one end of the antenna element 3, and an anode having a DC blocking capacitor 4. A tuning circuit is constituted by the variable capacitance diode 2 connected to the. The connection point between the variable capacitance diode 2 and the capacitor 4 is connected to the antenna ground, that is, the ground of the case of the wireless communication device body 6 via the high frequency choke coil 5.

On the other hand, in the main body 6 of the wireless communication device, the voltage control oscillator 7, the variable frequency divider 8 for dividing the oscillation frequency of the voltage control oscillator 7 based on the transmission / reception frequency setting signal, and the phase of the output of the variable frequency divider And a phase comparator 10 that compares the phase of the oscillation output of the reference oscillator 9 with each other, and a PLL circuit including a low-pass filter 11 that integrates the phase comparison output of the phase comparator 10 and supplies the output as a frequency control voltage to the voltage controlled oscillator 7. A variable frequency oscillator constituted by 12 is provided.

The frequency control voltage of the voltage controlled oscillator 7 output from the low pass filter 11 is the high frequency choke coil 1.
It is supplied to the power feeding portion of the antenna element 3 via 3. The power feeding portion of the antenna element 3 is the wireless communication device main body 6
It is connected to the antenna input / output terminal inside.

In the antenna 1 of the present embodiment configured as described above, the antenna element 3, the DC blocking capacitor 4 and the variable capacitance diode 2 form a tuning circuit. On the other hand, the frequency division ratio of the variable frequency divider 8 is controlled based on the transmission / reception frequency setting signal, and the output frequency of the PLL circuit 12 is controlled to a frequency corresponding to the transmission frequency and the reception frequency of the wireless communication device. In this case, the high frequency component of the frequency control voltage of the voltage controlled oscillator 7 is blocked by the high frequency choke coil 13, and the frequency control voltage of which the high frequency component is blocked is applied to the power feeding portion of the antenna element 3.

Therefore, the frequency control voltage in which the high frequency component is blocked is applied to the cathode side of the variable capacitance diode 2 via the antenna element 3. By this application, the capacitive reactance of the variable capacitance diode 2 is controlled to be the capacitive reactance inversely proportional to the frequency control voltage. As a result, the inductive reactance of the antenna element 3 and the capacitive reactance of the variable capacitance diode 2 tune to the frequency used by the wireless communication device.

Therefore, the tuning frequency of the antenna 1 is changed according to the change of the transmission frequency and the reception frequency of the radio communication device, and the tuning frequency of the antenna 1 is changed corresponding to the used frequency. An antenna characteristic that is tuned in a band can be obtained, and a single antenna can provide sufficient performance.

The cathode side of the variable capacitance diode 2 may be connected to a predetermined portion of the antenna element 3.

Although the high frequency choke coils 5 and 13 may be resistors in the above-described embodiment, the high frequency choke coil 13 is preferably a series circuit of a resistor and a high frequency choke coil. This is because when the antenna 1 is detached from the wireless communication device main body 6, the frequency control voltage is directly output, so that a short circuit can be prevented.

In the above-described embodiment, the case of a single frequency band antenna has been described, but it can be applied to a two-band antenna, and in this case, a part of the antenna element 15 as in the modification shown in FIG. Can be applied to the antenna element 13 that forms the element.

[0017]

As described above, according to the antenna of the present invention, the frequency control voltage of the voltage controlled oscillator is applied to the variable capacitance diode via the antenna element to control the capacitive reactance of the variable capacitance diode. Because of the configuration, due to the inductive reactance of the antenna element and the capacitive reactance exhibited by the variable capacitance diode, the antenna is tuned to the operating frequency of the wireless communication device, and is tuned in a wide frequency band in which the wireless communication device operates, One antenna has an effect that sufficient performance can be obtained in a wide frequency band.

Therefore, it is not necessary to prepare a plurality of antennas, and there is an advantage that the antennas are not lost.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 2 is a circuit diagram showing a main part of a modified example of the present invention.

FIG. 3 is a circuit diagram showing a configuration of a conventional example.

[Explanation of symbols]

 1 Antenna 2 Variable Capacitance Diode 3 Antenna Element 4 DC Blocking Capacitor 5 and 13 High Frequency Choke Coil 6 Radio Communication Device Main Body 12 PLL Circuit

Claims (1)

[Claims] 1. An antenna of a wireless communication device, which comprises a PLL circuit having a frequency-controlled oscillator and an antenna tuned to a frequency to be used, and operates at a plurality of frequencies, the antenna element being connected to an antenna element and a power feeding section of the antenna element. A DC blocking capacitor and a variable capacitance diode connected between a predetermined part of the antenna element and the DC blocking capacitor constitute a tuning circuit, and the connection point between the variable capacitance diode and the DC blocking capacitor is a high frequency choke coil, or An antenna characterized in that it is connected to an antenna ground via one of resistors, a frequency control voltage of the voltage controlled oscillator is superimposed on the power feeding portion, and is tuned to a used frequency.