JPS6119183B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to receiving devices such as television receivers and FM receivers.

The inventor bent a transmission conductor path to configure an antenna element having a distributed constant inductance, and succeeded in downsizing the antenna by using this antenna element.

The present invention provides a receiving device that can perform excellent reception using such a miniaturized antenna.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, the antenna circuit 1 is constructed as follows. 2a and 2b are a pair of antenna elements made by bending conductors with low electrical resistance such as copper, aluminum, iron, etc., and the conductors are continuously arranged and alternately distributed in the length direction of the element and in the direction perpendicular to it. This results in a distributed constant inductance. Since the reactance of the antenna elements 2a, 2b can be canceled by this distributed constant inductance, the feed terminals 3a, 3
Since the impedance seen from b can be set to the required value at the required frequency, and a conductor in the form of a foil or cylindrical wire with a large surface area can be used, the loss can be extremely reduced. An antenna with a large operating gain can be constructed using antenna elements 2a and 2b that are smaller in size. 4a, 4b are power feeding terminals 3a, 3 of each antenna element 2a, 2b.
This is a variable reactance circuit connected to b, and includes variable capacitance diodes 5a and 5b as variable elements. By appropriately controlling the capacitance values of the diodes 5a and 5b, the resonance frequency r of the variable reactance circuits 4a and 4b, which changes as shown in FIG. 2, can be appropriately set.
The reactance of a and 2b can be controlled. 6 is a capacitor for impedance adjustment connected between the feed terminals 3a and 3b, 7 is a balanced/unbalanced converter, 8 is a high-pass filter for passing high frequency reception signals, 9 is an output terminal, and 10 is a capacitor from the receiver. A low-pass filter that passes the control signal,
11 is a frequency divider, 12 is a phase detector, 13 is a low-pass filter, 14 is a voltage controlled oscillator (VCO), 1
5 is a frequency divider, and the phase detector 12 to frequency divider 15 constitute a well-known PLL circuit.
A frequency discrimination circuit 16 is configured by the PLL circuit and the frequency divider 11.

On the other hand, 17 indicates the high frequency stage of the receiver,
18 is a synthesizer section composed of a PLL, 19 is a reference oscillator, 20 is a phase comparator, 21 is a low-pass filter, 22 is a VCO, 23 is a frequency divider, 24 is a program counter, and 25 is an output signal of the frequency divider 23 26 is a high-pass filter that passes the high frequency reception signal from the antenna circuit 1, 27 is an input terminal of the receiver, 28 is a terminal connected to the front end, 29 is a terminal connected to the mixer, 30 is a terminal to which a code for setting the reception frequency is applied.

The output terminal 9 of the antenna circuit 1 and the input terminal 27 of the receiver 17 are connected by a high frequency coaxial cable 31.

In the above configuration, the operation of the antenna circuit 1 will be explained first.

Frequency ₁ of antenna elements 2a, 2b ~
The element pattern is designed so that the impedance in ₂ to ₃ becomes as shown in Fig. 3A, and then the resonant frequency r of the variable reactance circuits 4a and 4b is
If is set to a required value so that it becomes a positive reactance at frequencies ₁ to ₂ to ₃ , the impedance at that time rotates as shown in FIG. 3B. Since a capacitor 6 for impedance adjustment is inserted between the power supply terminals 3a and 3b,
The impedance is as shown in Figure 3C, and the frequency
At _{step 2} , synchronization can be achieved.

Therefore, by changing the values of the variable capacitance diodes 5a and 5b, the resonant frequency r is changed, thereby changing the reactance added to the antenna elements 2a and 2b, and the frequency ₁ to _{2 is changed} .
The tuning condition may be satisfied in all bands of _.about.3 .

In order to realize this, in the above embodiment, the frequency divider 2 of the synthesizer section 18 provided in the receiver 17
The output of No. 3 is used as a control signal. In other words, this control signal is passed through the low pass filter 2.
5. Supply the control signal to the antenna circuit 1 via the input terminal 27 and the coaxial cable 31, and further apply this control signal to the frequency divider 11 via the low-pass filter 10 to step down the frequency to an appropriate frequency, and then apply the control signal to the PLL circuit 12.
~ 15, a DC voltage corresponding to the frequency of the control signal is extracted from the output side of the low-pass filter 13, and is applied to the variable capacitance diodes 5a, 5b.
I am trying to apply it to If you do this,
Tuning can be remotely controlled from the receiver 17 side. The high-frequency reception signal from the antenna circuit 1 is sent to the output terminal 9 via the bypass filter 8, and is supplied to the front end via the coaxial cable 31, the input terminal 27, the high-pass filter 26, and the terminal 28. The numbers in Figure 1 are for the FM band in Japan (reception frequency 76MHz~
90MHz).

Further, as the frequency discrimination circuit 16, a pulse count detector, a Foster-Seeley type detector, a ratio type detector, a two-departure resonator type detector, a slope detector, etc. may be used. Furthermore, it goes without saying that if the frequency division ratio of the frequency divider 11 is appropriately set, the output of the VCO 22 may be directly used as a control signal. Further, the variable reactance circuits 4a and 4b may be connected to positions other than those shown.

As described above, the present invention provides a frequency discrimination circuit in an antenna circuit having a miniaturized antenna element, supplies the VCO output of a synthesizer receiver or its frequency-divided output as a tuning control signal to the frequency discrimination circuit, and Since the DC voltage output from the frequency discrimination circuit is applied to the variable capacitance diode provided in the antenna circuit, it is possible to remotely control the tuning of the antenna circuit from the receiver side for excellent reception. can.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG.
FIG. 3 is an explanatory diagram of the operation. 1... Antenna circuit, 2a, 2b... Antenna element, 4a, 4b... Variable reactance circuit, 5a, 5b... Variable capacitance diode, 6...
Capacitor for impedance adjustment, 16... Frequency discrimination circuit, 17... Receiver, 18... Synthesizer section, 31... High frequency coaxial cable.

Claims (1)

[Claims] 1. An antenna section having an antenna element, a variable reactance circuit connected to an appropriate position of the antenna element, and a frequency discrimination circuit;
a PLL synthesizer receiver, the output terminal of the antenna section and the input terminal of the receiver are connected by a high frequency coaxial cable, and a high frequency received signal from the antenna section is transmitted via the high frequency coaxial cable, The PLL circuit of the above receiver
A receiving device configured to supply an output of a VCO or its frequency-divided output to a frequency discriminator of the antenna section via the high frequency coaxial cable, and supply an output of the frequency discriminator to a variable reactance circuit of the antenna section. 2. The receiving device according to claim 1, wherein the antenna element is a zigzag-shaped element in which the transmission conductor path is folded and has a distributed constant inductance. 3. The receiving device according to claim 1 or 2, characterized in that a voltage variable capacitance diode is used as the variable reactance element of the variable reactance circuit.