JPS5942725Y2 - 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, in a box-shaped conductor case 1, a plurality of TEM mode resonators 4 loaded with a dielectric material 3 are arranged in cascade around a line 2 whose open end is formed into a disk shape. Coaxial connectors 5 and 6 for input and output are provided on both end faces of the case 1.

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 TEM mode resonator 4, the degree of adhesion between the line 2 and the dielectric 3 has a sharp effect on the resonant frequency, but in reality, both the line 2 and the dielectric 3 have processing tolerances, so they must always be in close contact with each other. That was impossible.

For this reason, the center frequency of each resonator 4 varies greatly, and adjustment tends to be time-consuming.

In view of the above-mentioned points, the present invention aims to reduce variations in the center frequency of each resonator and to provide a distributed constant filter that facilitates adjustment work.

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

In FIG. 3, the line 2 consists of a center conductor 20 loaded with a dielectric 3 and a disk-shaped capacitive electrode section 21 separate from the center conductor 20.

As shown in FIG. 4, the center conductor 20 has a hollow pipe shape except for the short-circuited end at the lower part, and a split 22 is formed in the axial direction in this hollow pipe-shaped part so as not to impede the high-frequency current. A caulking portion 23 is integrally formed at the end.

On the other hand, the disc-shaped capacitive electrode part 21 has a recess 24 and a mounting protrusion 2.
5 is formed, and a recess 26 and a mounting protrusion 27 are formed in the box-shaped conductor case 1.

Then, the line 2 is formed by passing the caulking part 23 through the mounting protrusion 27 of the box-shaped conductor case 1 with the dielectric 3 fitted to the center conductor 20, and caulking the caulking part 23, and rounding the tip of the central conductor 20. The center conductor is fixed to the box-shaped conductor case 1 by passing it through the mounting protrusion 25 of the plate-shaped capacitor electrode part 21 and folding and caulking the tip of the center conductor.

Then, a pin 28 made of elastic plastic or the like is press-fitted inside the center conductor 20. Since the center conductor 20 has a split 22, the press-fitting of the pin 28 causes it to be expanded in the radial direction, and the inner periphery of the dielectric 3 is expanded. Closely adheres to the surface.

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

According to the above embodiment, the center conductor 20 of the line 2 is formed into a pipe shape having a split 22 1-1. An elastic pin 28 is press-fitted inside the center conductor 20, and the center conductor 20 is attached to the dielectric 3. Since they can be brought into close contact with each other, it is possible to reduce variations in the center frequency of each resonator 4 due to varying degrees of contact between the center conductor 20 and the dielectric 3.

Therefore, each resonator 4 can be adjusted easily.

Furthermore, the dimensional tolerance of the dielectric 3 can be relaxed, and the processing accuracy can be lowered accordingly, so that manufacturing costs can also be reduced.

Note that the disk-shaped capacitive electrode portion 21 can be fixed to the center conductor 20 by welding, soldering, etc. in addition to caulking, and the center conductor 20 can also be fixed to the box-shaped conductor case 1 by caulking. In addition to processing, it can be performed by welding, screwing, etc.

Further, the number of splits 22 can be increased or decreased as appropriate.

As described above, according to the present invention, a distributed constant filter is obtained in which variations in the center frequency of each resonator are reduced and adjustment can be easily performed.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view showing a basic distributed constant type filter.
Fig. 2 is a plan view with the top of the box-shaped conductor case removed; Fig. 3 is a partial sectional view showing an embodiment of the distributed constant filter according to the present invention; Fig. 4 shows the center conductor. FIG. 1... Box-shaped conductor case, 2... Line,
3...Dielectric material, 4...TEM mode resonator, 10...Top part, 11...Capacitive electrode, 20...Center Conductor, 21...disc-shaped capacitor electrode section, 22...split, 23...
・Caulking part, 24.26...Concave part, 25.27
...Mounting protrusion, 2B...pin.

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 short-circuited at one end and open at the other end, and a capacitance is provided at the open end of the line, at least a part of the center conductor of the line is divided. A distributed constant type filter characterized in that it is formed into a pipe shape with an elastic pin press-fitted inside the central conductor.