JPH05315810A - Voltage controlled filter - Google Patents

Abstract

PURPOSE:To attenuate a frequency close to a pass band frequency largely with simple configuration by inter-coupling dielectric resonators with a bridging metallic wire. CONSTITUTION:A bridging metallic wire 1 is provided on a position corresponding to the upper ends of dielectric resonators 11, 12, 13, 14 at the outside of a case 60. One end of the metallic wire 1 is inserted inot the case 60 via the throughhole 60a of the case 60 and passes through the vicinity of the inner conductor 11a of the resonator 11 and is connected to a flank conductor 11b. Furthermore, the other terminal of the metallic wire 1 is inserted into the case 60 via the throughhole 60a of the case 60, passes through the vicinity of the inner conductor 13a of the resonator 13 and is opened on the flank conductor 13b. A pole is formed in the frequency characteristic by using the bridging metallic wire 1 to bridge the resonators 11 and 13 of the voltage controlled filter. Thus, the frequency in the vicinity of the pass band is largely attenuated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage controlled filter capable of varying the center frequency of the pass band by adjusting the bias voltage.

[0002]

2. Description of the Related Art In a conventional voltage controlled filter, as shown in FIG. 3, one end of each of inner conductors 11a, 12a, 13a, 14a of four dielectric resonators 11, 12, 13, 14 is coupled. Are connected in parallel via the capacitors 21, 22, 23, 24, 25. The coupling capacitors 21 and 25 located at the ends have an input terminal 101 and an output terminal 102, respectively. Furthermore, the voltage control filter 1
Internal conductors 11a, 12a, 13 of 1, 12, 13, 14
At the other ends of a and 14a, variable frequency width adjusting capacitors 31, 32, 33 and 34, bias voltage supplying resistors 41, 42, 43 and 44 and bias terminal 103, respectively.
104, 105 and 106 are connected in series. Also,
A varactor diode 5 whose one end is grounded to the case 60 in parallel with the bias voltage supply resistors 41, 42, 43, 44.
1, 52, 53, 54 are connected.

In the conventional voltage controlled filter having the above structure, the varactor diode 5 can be adjusted by adjusting the bias voltage applied to the bias terminals 103, 104, 105 and 106.
The capacities of 1, 52, 53, 54 change, and the center frequency of the pass band can be changed. In such a conventional voltage controlled filter, in order to largely attenuate the frequency closer to the pass band, the number of stages of the voltage controlled filter main body (for example, the voltage controlled filter shown in FIG. 3 has four stages). Was taken).

[0004]

In the above-mentioned conventional voltage controlled filter, when the number of stages of the voltage controlled filter body is increased in order to largely attenuate the frequency closer to the pass band, the voltage controlled filter is increased. There is a problem that the number of parts that make up the filter increases and the filter body becomes large. Also,
Since the number of varactor diodes also increases as the number of stages of the voltage controlled filter increases, there is a problem that it becomes difficult to adjust the pass band of the voltage controlled filter.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a voltage-controlled filter which can greatly attenuate frequencies closer to the pass band without increasing the number of stages. ..

[0006]

In order to achieve the above object, the present invention provides a voltage-controlled filter in which the center frequency of the pass band can be varied by adjusting the bias voltage. A bridging metal located near the inner conductor of the dielectric resonator and open or grounded, and the other end near the inner conductor of another dielectric resonator and open or grounded It is configured with lines.

[0007]

According to the voltage controlled filter having the above-mentioned structure, the dielectric resonators are coupled by the bridging metal wire, so that a pole is formed in the frequency characteristic and the frequency near the pass band is greatly attenuated.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1A and 1B show a voltage controlled filter according to the present embodiment. FIG. 1A is a schematic front view of the circuit, FIG. 1B is a schematic plan view of the circuit, and FIG. 1C is a schematic side sectional view of the circuit. It is a figure. Further, since the voltage controlled filter according to the present embodiment has a configuration in which a bridging metal wire is added to the conventional voltage controlled filter, the same parts as those in the conventional art are designated by the same reference numerals. And detailed description thereof will be omitted.

In the figure, 1 is a bridging metal wire,
Outside the case 60 and on the dielectric resonators 11, 12, 13,
It is provided at a position corresponding to the upper end of 14. One end of the bridging metal wire 1 is inserted through the through hole 60a of the case 60,
It is inserted in the case 60, passes near the internal conductor 11a of the dielectric resonator 11, and is connected to the side conductor 11b. Further, the other end of the bridging metal wire 1 is inserted into the case 60 through the through hole 60b of the case 60, passes near the internal conductor 13a of the dielectric resonator 13, and passes through the side surface conductor 13.
It is open on b.

FIG. 2 is a graph showing the frequency characteristics of the voltage controlled filter according to the present embodiment. The solid line part indicates the present embodiment,
The dotted line shows the conventional one.

As shown in FIG. 2, the voltage controlled filter of the present embodiment having the above-mentioned structure has dielectric resonators 21 and 23.
Is bridged by the bridging metal wire 1 to form a pole P (see FIG. 2) in the frequency characteristic. This allows
Frequencies near the pass band are greatly attenuated. Further, the frequency value generated by the pole and the size of the pole are determined by the respective end portions of the bridging metal wire 1 and the inner conductors 2 corresponding thereto.
Adjust by changing the distance between 1a and 23a.

According to the voltage controlled filter of the present embodiment having the above-mentioned structure, the frequency in the vicinity of the pass band can be greatly attenuated to 1 by a simple structure in which one bridging metal wire is added. it can.

The present invention is not limited to the above embodiment. For example, even if both ends of the bridging metal wire 1 are connected to each other and the other is opened, or both are connected, or both are opened, the effect to be exerted does not change.

[0014]

As described above, according to the voltage controlled filter of the present invention, the frequency close to the pass band can be greatly attenuated with a simple structure without increasing the number of stages.

[Brief description of drawings]

1A and 1B show a voltage control filter according to an embodiment of the present invention, in which FIG. 1A is a schematic front view of the circuit, FIG. 1B is a schematic plan view of the circuit, and FIG. 1C is a schematic side view of the circuit. FIG.

FIG. 2 is a graph showing frequency characteristics of the voltage controlled filter according to the present embodiment.

3A and 3B show a voltage controlled filter according to a conventional example, where FIG. 3A is a schematic front view of the circuit, FIG. 3B is a schematic plan view of the circuit, and FIG. 3C is a schematic side sectional view of the circuit. It is a figure.

[Explanation of symbols]

1 ... Bridging metal wire 11, 12, 13, 14 ... Dielectric resonator 11a, 12a, 13a, 14a ... Inner conductor 11b, 12b, 13b, 14b ... Side conductor 21, 22, 23, 24, 25 ... Coupling Capacitors 31, 32, 33, 34 ... Variable frequency width adjusting capacitors 41, 42, 43, 44 ... Bias voltage supply resistors 51, 52, 53, 54 ... Varactor diode 101 ... Input terminal 102 ... Output terminal 103, 104 , 105, 106 ... Bias terminal

Claims (1)

[Claims] 1. By adjusting the bias voltage,
In a voltage controlled filter that can vary the center frequency of the pass band, one end is located near the inner conductor of one dielectric resonator and is open or grounded, and the other end is the other dielectric. A voltage-controlled filter characterized in that it is provided with a bridging metal wire that is located near the inner conductor of the resonator and that is open or grounded.