JPS62181504A - Filter - Google Patents

Abstract

PURPOSE:To miniaturize the filter and to facilitate the phase adjustment of the filter by connecting a strip line circuit between an external circuit and an input stage or an output stage of a distributed constant type filter comprising a dielectric coaxial resonator and using the filter as the phase adjusting element. CONSTITUTION:A strip line 22 if formed to one major surface of an insulating ceramic base 21 in a strip line circuit 13. Wide parts 22a, 22a are provided to the strip line 22 at two positions; one end and the other end, and a pi type equivalent circuit comprising lumped circuit constants L, C (C is a static capacitance formed between the wide parts 22a, 22a and an earth electrode 23, and L is an inductance of the strip line 22) is formed. Thus, the electric angle Q is changed by changing the area of the wide parts 22a, 22a of the strip line 22 or the width of the strip line 22.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a distributed constant filter constituted by a dielectric coaxial resonator.

(Prior art) Conventionally, several 100 MI (as a z-band filter, L
Those using a C8 resonator and those using a coaxial resonator are well known, but they are structurally unstable or complicated, have unsatisfactory characteristics, take time to adjust, and cannot reduce costs. There were other problems.

For this reason, as a filter in the frequency band of several 100 MI (z), for example, a dielectric coaxial resonator in which a multi-stage resonant unit is constructed in a dielectric block made of a titanium oxide-based ceramic dielectric, or a dielectric coaxial resonator similar to that mentioned in A filter using a dielectric coaxial resonator using a cylindrical dielectric material made of a dielectric material has been put into practical use.

Incidentally, the phase adjustment of this type of filter is as shown in FIG. 6 for a filter formed by coupling a dielectric coaxial resonator 1 using a cylindrical dielectric material with a coupling capacitor C8.
Between the input terminal 2 of the filter connected to an external circuit and the dielectric coaxial resonator l of the manual stage of the filter, or between the output terminal 3 of the filter connected to the external circuit and the dielectric coaxial resonator l of the output stage of the filter This is done by inserting a transmission line 4 such as a coaxial cable between the

For example, in Japanese Patent Publication No. 58-6404, as shown in FIG. It is disclosed that a coaxial cable 9 is connected to the filter 9, and the phase of the second filter 8 is adjusted depending on the length of the coaxial cable 9.

However, due to its structure, the coaxial cable 9 has a large diameter and is difficult to bend, making it difficult to accommodate the coaxial cable 9 in a narrow space. For this reason, when the shape of the filter becomes large, there arises the problem of ν).

In addition, the coaxial cable 9 has a problem in that terminal processing is troublesome, and the length of the coaxial cable 9 must be accurate in order to adjust the phase of the filter, making it difficult to adjust the phase of the filter.

(Object of the Invention) An object of the present invention is to provide a filter that is small and whose phase can be easily adjusted.

(Structure of the Invention) Therefore, the present invention is characterized in that a stripline circuit is used for phase adjustment.

This stripline circuit is connected between an external circuit such as an input stage or an output J stage of a distributed constant type filter constituted by a dielectric coaxial resonator.

(Effects of the Invention) According to the present invention, since a stripline circuit, which is very small compared to a transmission line such as a coaxial cable, is used as a phase adjustment element, the shape of the filter can be reduced and By changing the stripline pattern and dimensions of the stripline circuit, the phase of the filter can be easily adjusted.

(Example) Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The filter 11 shown in FIG. 1 is constructed from a dielectric block 2, and its phase is adjusted by a slip I/slip line circuit 13.

1. Filter II has through holes +4, 14, . , . . , 14 are provided, and an inner conductor 16 is formed on the inner surface of each through hole 14, and an outer conductor 17 is formed on the four sides of the dielectric block 12 surrounding each of the through holes 14. 16, the outer conductor I7, and the dielectric block 12 interposed therebetween form a resonant unit, which is a well-known structure. As shown in FIG. 2, each of the inner conductors 16 and the outer conductor I7 are
The through holes 14 of the dielectric block 12 are mutually short-circuited by short-circuiting conductors 18 formed on both sides of the open end side. Through holes +4.14 formed in a row in the dielectric block 12
．． . . , 14, through holes 14 at both ends. ．． On the 14th,
For example, as shown in FIG. 3, vertical metal coupling pins 20 and 20 are loosely fitted into support fittings 19 formed by punching out a metal plate (not shown) into a cross shape, respectively. A metal fitting 19 is soldered to a shorting conductor 18 formed on the dielectric block 12. The means for coupling with the external circuit is not limited to this, and conventionally known means for capacitive coupling on the open end side may be used.

On the other hand, in the strip line circuit 13, as shown in FIG. A ground electrode 23 is formed on the entire surface of the other main surface of the ceramic substrate 21. ” - The strip line 22 has two wide parts 22 at one end and the other end.
a, 22a, and due to the capacitance C formed between the wide portions 22a, 22a and the ground electrode 23 and the inductance of the strip line 22, a lumped constant as shown in FIG. It can be expressed as a circuit or has a π-type equivalent circuit made of C.

The characteristic impedance Z of this stripline circuit I3
. and electrical angle θ are expressed by the following equations (1) and (2), respectively, where ω is the angular frequency of the passing signal frequency.

As shown in FIG. 1, the strip line circuit 13 has the ground electrode 23 conductively bonded to the outer conductor 17 of the dielectric block 12 by solder or the like. Ru. One end of the strip line 22 of the strip line circuit I3 is connected to the metal coupling pin 20, and the other end is connected to the filter 11.
The input terminal 24 is connected to an external circuit (not shown).

Note that another metal coupling pin 20 of the filter 11 is connected to an output terminal 25 of the filter 11.

In such a configuration, the characteristic impedance Z of the stripline circuit 13 is expressed by equation (1).

while keeping it at a constant value equal to the output impedance of the external circuit connected to the input terminal 24,
) can change the electrical angle θ. Specifically, the wide parts 22a, 22a of the strip line 22
By changing the area of the slip line 22 or the width of the slip line 22, the double electrical angle can be changed.

Thereby, the phase of the signal output from the output terminal 25 of the filter 11 can be easily adjusted using the small-sized stripline circuit 13.

Note that in the above embodiment, the stripline circuit 13
1. Another metal coupling pin 2 of the filter 11.
0 and the output terminal 25.

In addition to the filter 11 that uses a dielectric coaxial resonator, the structure of which is shown in FIG. Can be applied.

[Brief explanation of drawings]

Fig. 1 is a perspective view of an embodiment of the filter according to the present invention, Fig. 2 is a vertical cross-sectional view of the dielectric block portion of the filter shown in Fig. 1, and Fig. 3 is a perspective view of a metal coupling pin and its support plate. , Figure 4 is a perspective view of a stripline circuit, Figure 5 is an equivalent circuit diagram of the stripline circuit in Figure 4 expressed as a lumped constant circuit, Figure 6 is a circuit diagram of a conventional filter, Figure 7 is a coaxial FIG. 2 is an explanatory diagram of a duplexer using a cable as a phase adjustment element. 11. Filter using dielectric block, ■3 Strip line circuit, 20. Metal coupling pin, 22. Strip line, 24. Input terminal, 25
...Output terminal. Patent applicant: Murata Manufacturing Co., Ltd. Agent: Patent attorney: Mr. Aoki and 2 others = 8- Figure 1 Figure 4

Claims (1)

[Claims] (1) In a distributed constant filter composed of dielectric coaxial resonators, a strip line circuit for phase adjustment is connected between the input stage or output stage of this filter and the external circuit. Featured filters.