JPS5942723Y2 - Distributed constant filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a distributed constant filter having a resonator loaded with a dielectric material.

A line with a length of λ/4 (λ: wavelength) with one end short-circuited and the other end open operates as a resonator, and by arranging multiple such resonators in parallel and connecting them by appropriate means. A distributed constant filter that combines these is small in size and is known as a comb filter.

Such distributed constant type filters are widely used especially in the microwave band.

Furthermore, for the purpose of miniaturization, the line is loaded with a dielectric material with a high relative permittivity, and a capacitor for adjusting the center frequency is provided at the open end of the line, thereby making the distributed constant filter more compact and improving its characteristics. Proposed by the applicant.

FIGS. 1 and 2 show the basic configuration of this type of distributed constant filter.

In these figures, a plurality of resonators 4 loaded with a dielectric material 3 are arranged in series in a box-shaped conductor case 1 around a line 2 whose open end is formed into a disk shape. Coaxial connectors 5.6 for input and output are provided on both end faces of the connector.

On the other hand, the upper surface part 10 of the box-shaped conductor case 1 has the line 2
A plurality of disc-shaped capacitor electrodes 11 are arranged facing the open end of the capacitor electrode 11 .

By the way, in the case of the above-mentioned distributed constant type filter, the center frequency is determined by the dimensions of the line 2 and the dielectric 30, the area and position of the capacitor electrode 110, etc., but in practice it is difficult to assemble it so that it exactly matches the predetermined center frequency. Therefore, a means for adjusting the resonant frequency of each resonator 4 is required.

In view of the above points, the present invention aims to provide a distributed constant filter that allows rough and fine adjustment of the resonant frequency of a resonator with a simple structure.

Embodiments of the distributed constant filter according to the present invention will be described below with reference to the drawings.

3 and 4 show a first embodiment of the present invention.

In these figures, a screw is carved into the curved surface of a large-diameter main capacitance electrode 11A with a large electrode surface area, and this main capacitance electrode 11A is screwed into the upper surface part 10 of the box-shaped conductor case 1. Ru.

A female screw is formed in the center of the main capacitor electrode 11A, and a small diameter sub-capacitor electrode 11B has a screw carved on the circumference.
is screwed into the female screw portion.

Note that the other configurations are the same as those in FIGS. 1 and 2 described above.

In the first embodiment, the main capacitance electrode 1 is twisted so that the resonance frequency of each resonator 4 is close to a predetermined center frequency.
1A to change the distance between the open end of the line 2 and the capacitive electrode section 20, the resonant frequency is coarsely adjusted, and then the sub-capacitive electrode 11B is rotated to finely adjust the resonant frequency. It is possible to accurately set the resonant frequency to a predetermined center frequency.

As explained above, according to the first embodiment, the capacitance can be greatly varied by rotating the large-diameter main capacitor electrode 11A, and the capacitance can be finely adjusted by rotating the sub-capacitor electrode 11B. Can be adjusted.

Therefore, both coarse and fine adjustment of the resonant frequency is possible, the variable range of the resonant frequency can be increased, and setting to a predetermined center frequency is easy.

Moreover, since the main capacitor electrode 11A and the sub-capacitor electrode 11B may be simply screw bodies, they are easy to manufacture and have a simple structure.

5 and 6 show a second embodiment of the present invention.

In these figures, a large-diameter main capacitance electrode 11C is screwed onto the top surface 10 of the box-shaped conductor case 1, and a small-diameter sub-capacitance electrode 11D is screwed onto the top surface 10 near the main capacitance electrode 11C. Ru.

Note that the other configurations are the same as those in FIGS. 1 and 2 described above.

Also in the second embodiment, the main capacitance electrode 11C can perform coarse adjustment of the resonance frequency, and the sub-capacitance electrode 11D can perform fine adjustment.

Further, since it is not necessary to form a female screw in the main capacitor electrode 11C, there is an advantage that the structure can be further simplified.

In each of the above embodiments, after adjusting the main capacitance electrode and the sub-capacitance electrode, it is possible to use a lock nut or the like in order to fix them.As described above, according to the present invention, a simple A distributed constant filter is obtained which allows coarse and fine adjustment of the resonant frequency of a resonator depending on the structure.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view showing a basic distributed constant type filter.
Fig. 2 is a plan view of the box-shaped conductor case with the top removed, Fig. 3 is a partial cross-sectional view showing the first embodiment of the distributed constant filter according to the present invention, and Fig. 4 is the same as that of Fig. 3. FIG. 5 is a partial sectional view showing the second embodiment, and FIG. 6 is a view taken along the line Vl-Vl in FIG. 5. 1... Box-shaped conductor case, 2... Line,
3... Dielectric, 4... Resonator, 10...
...Top part, 11...Capacitance electrode, 11A
, 11C... Main capacitance electrode, 11B, 11D...
... Sub-capacitance electrode, 20 ... Capacity electrode part.

Claims (1)

[Scope of utility model registration request] In a distributed constant filter having a resonator in which a dielectric material is loaded on a line with one end short-circuited and the other end open, and a capacitance is provided at the open end of the line, a capacitance is formed between the line and the open end of the line. 1. A distributed constant type filter characterized in that a main capacitance electrode is screwed onto a case, and a sub-capacitance electrode is screwed onto a portion of the main capacitance electrode or a portion of the case near the reading capacitance electrode.