JPH09284009A - Dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily adjust and set connection and external connection between adjacent resonance equipments to a required value without changing other compositions such as an external size, etc., by forming inner conductive non- forming parts which are formed over the whole periphery of resonance equipment holes so as to be inclined as against an opening surface. SOLUTION: The inner conductive non-forming parts 6 are formed over the whole periphery of the resonance equipment holes 2a and 2b by prescribed width and also formed by inclination as against the opening surface. Thus, the circumferential length of the inner conductive non-forming parts 6 in the adjacent resonance equipment holes 2a and 2b is made to be longer than the conventional one and stray capacitance Cs becomes larger. Since the opposed areas of inner conductors 3 and input/output electrodes 5 become larger, respective kinds of outer coupling capacity Ce become larger than the conventional ones so that strong outer coupling is obtained. Then, the inclination direction of the respective inner conductive non-forming parts 6 is changed so that respective externally coupled capacitances Ce are optionally changed and desired outer coupling is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter having resonator holes formed in a dielectric block.

[0002]

2. Description of the Related Art Conventionally, by forming an open end at a position deeper than the opening surface of a resonator hole, the influence of electromagnetic field leakage can be reduced and desired characteristics can be easily obtained. There is a dielectric filter having a structure as shown in. FIG. 4A is an external perspective view as seen from the open end surface.
(B) is sectional drawing in the central horizontal surface of (a). In the following figures, the dot-filled portions indicate the portions where the base material of the dielectric block is visible (conductor non-formation portions).

As shown in FIG. 4, this dielectric filter penetrates a pair of opposing end faces of a substantially rectangular parallelepiped dielectric block 1 and has an inner conductor 3 formed on its inner face, for example, two resonances. 2a and 2b are formed, and an outer conductor 4 is formed on substantially the entire outer surface of the dielectric block 1.
Input / output electrodes 5 and 5 are formed at predetermined locations.

Each of the inner conductors 3 and 3 has a non-formed inner conductor portion 6 (hereinafter, inner conductor non-formed portion) in the vicinity of one opening surface (hereinafter referred to as an open side end surface) of the resonator holes 2a and 2b. Will be written)
Is provided and is opened (separated) from the outer conductor 4, and the other opening surface (hereinafter, referred to as a short-circuit side end surface) is short-circuited (conducted) with the outer conductor 4.

The inner conductor non-forming portion 6 forms the open end of the resonator, and has a predetermined width and is located at a position recessed from the open end face in parallel with the open end face and around the entire circumference of the resonator holes 2a, 2b. It is formed over.

[0006] This dielectric filter has resonator holes 2a,
It is composed of two resonators formed for each 2b, and the resonators are coupled to each other by the stray capacitance Cs generated in the inner conductor non-forming portion 6, and between the input / output electrode 5 and the corresponding inner conductor 3. External coupling is obtained by the generated external coupling capacitance Ce.

By adjusting the stray capacitance Cs by changing the width of the inner conductor non-forming portion 6 and the like, the coupling between both resonators is changed, and the formation position and area of the input / output electrodes 5 and 5, the inner conductor non-forming area. The external coupling capacitance Ce is adjusted by changing the position of the forming portion or the like to obtain proper external coupling.

[0008]

However, in order to obtain a larger stray capacitance Cs, the width of the inner conductor non-formation portion is narrowed down due to the limitation of processing technology, and desired electrical characteristics can be obtained. I couldn't do it. That is,
Although the stray capacitance Cs increases as the width of the inner conductor non-forming portion is narrowed, the variation of the capacitance value also increases in proportion thereto, which adversely affects the electrical characteristics of the filter. Therefore, there is a fixed minimum value in the width of the inner conductor non-formed portion, and there is a limit in trying to obtain a larger stray capacitance Cs.

Further, even if a large stray capacitance Cs is obtained, the resonance frequency of the resonator is lowered. Therefore, it is necessary to shorten the axial length of the resonator in order to compensate for the reduction of the resonance frequency, and the inner conductor is not formed. There is a problem in that the positional relationship between the portion and the input / output electrode is broken and the external coupling capacitance Ce changes.

As described above, in the conventional dielectric filter, since the inner conductor non-forming portion is formed in parallel with the open side end face, there are many restrictions on the design and adjustment of the stray capacitance Cs and the external coupling capacitance Ce. However, there is a problem that desired electrical characteristics cannot be easily obtained.

Therefore, an object of the present invention is to make it possible to easily perform the stray capacitance Cs (coupling between resonators) without being influenced by the size of the dielectric block, the position of the input / output electrode, or the width of the inner conductor non-forming portion. An object of the present invention is to provide a dielectric filter capable of setting and adjusting the external coupling capacitance Ce (external coupling).

[0012]

In order to achieve the above object, the invention according to claim 1 provides a resonator hole in a dielectric block, and an inner conductor is formed on the inner surface of the resonator hole. In a dielectric filter having an outer conductor formed on an outer surface of a dielectric block and an inner conductor non-forming portion formed in the vicinity of at least one opening surface of the resonator hole, the inner conductor non-forming portion has a predetermined width. Is formed over the entire circumference of the resonator hole, and is formed so as to be inclined with respect to the opening surface.

According to the above structure, the inner conductor non-forming portion is formed to be inclined, and the circumferential length of the inner conductor non-forming portion is
It can be formed longer than the conventional one. Therefore, even with the same width of the inner conductor non-formed portion, a larger stray capacitance Cs can be obtained as compared with the conventional one. On the contrary, if the stray capacitance Cs is the same, the width of the inner conductor non-formed portion can be made larger than that of the conventional one, and the variation of the stray capacitance Cs due to the variation in processing of the width dimension can be reduced.

Further, the positional relationship between the input / output electrodes and the inner conductor non-forming portion can be appropriately set by arbitrarily changing the inclination direction of the inner conductor non-forming portion, so that a desired external coupling capacitance Ce can be obtained. be able to.

That is, it is easy to change the inclination angle or the inclination direction of the inner conductor non-formed portion without changing the outer dimensions, the dimensions after the resonator, the input / output electrode formation position or area, and the width of the inner conductor non-formed portion. The stray capacitance Cs and the external coupling capacitance Ce can be changed by various methods, so that desired electrical characteristics can be easily obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the drawings showing embodiments thereof. In the following drawings, the same reference numerals are given to those having the same or the same functions as the conventional example.

FIG. 1 is a sectional view of a dielectric filter according to the first embodiment of the present invention, which corresponds to FIG. 4 (b) of a conventional example.

In the dielectric filter of this embodiment, as shown in FIG. 1, the inner conductor non-forming portions 6 of the resonator holes 2a and 2b are formed to be inclined with respect to the end surface of the dielectric block. That is, each inner conductor non-forming portion 6 is formed at a position deeper from the open end surface on the side of the adjacent resonator hole and closer to the open end surface on the side surface on which the input / output electrode 5 is formed. . The configuration other than that the inner conductor non-forming portion 6 is inclined is the same as that of the conventional example shown in FIG. 4, and the description thereof is omitted.

The inner conductor non-forming portion 6 is formed in the resonator hole 2
It is formed by scraping off the conductor formed in a and 2b, and can be easily inclined by an automatic machine.

In this structure, adjacent resonator holes 2
Since the circumferential length of the inner conductor non-formed portion 6 of a and 2b is longer than that of the conventional one and the stray capacitance Cs is large, the coupling coefficient between both resonators, that is, the bandwidth of the filter is changed.

In the case of this embodiment, the coupling coefficient is increased, the bandwidth of the filter is increased, and a smaller insertion loss can be obtained. Further, since the facing area between the inner conductor 3 and the input / output electrode 5 becomes large, each outer coupling capacitance Ce becomes larger than that of the conventional one, and a strong outer coupling can be obtained.

By changing the inclination direction of each inner conductor non-forming portion 6, each outer coupling capacitance Ce can be arbitrarily changed and desired outer coupling can be obtained.

FIG. 2 is a sectional view of a dielectric filter according to the second embodiment of the present invention. As shown in FIG. 2, the resonator holes 2a and 2b of the dielectric filter of this embodiment are formed with a stepped portion at substantially the center of both end faces of the dielectric block 1. The inner conductor non-forming portions 6 of the resonator holes 2a and 2b are located deeper from the open end face on the adjacent resonator hole side,
On the side surface side where the input / output electrode 5 is formed, it is formed so as to be closer to the open side end surface.

In this structure, the open end face side is a resonator hole with a large inner diameter, and both resonators originally show capacitive coupling. Since the stray capacitance Cs increases and the degree of inductive coupling increases, both resonators are increased. The coupling between them is weakened and the bandwidth of the filter can be narrowed. Further, it is similar to the case of the first embodiment that desired outer coupling can be obtained by arbitrarily changing each outer coupling capacitance Ce.

The present invention is characterized in that the inner conductor non-forming portion formed in the vicinity of the opening surface of the resonator hole is formed to be inclined. The inclination angle and the inclination direction of the inner conductor non-forming portion are:
The present invention is not limited to the one described in the above embodiment, and the coupling angle or the external coupling capacitance between adjacent resonators can be changed by changing the tilt angle and the tilt direction without changing other configurations such as external dimensions. Can be easily set to a desired value.

That is, in addition to the method of inclining the inner conductor non-forming portion of the present invention, the inter-resonator capacitance and the inter-resonator capacitance can be changed by changing the width of the inner conductor non-forming portion and the formation position of the input / output electrode within an allowable range. The degree of freedom in setting and adjusting the external coupling capacitance can be greatly increased, and various filter characteristics can be easily realized with the dielectric filter having the same shape.

In each of the above embodiments, the dielectric filter having a two-stage structure has been described, but a one-stage trap having one resonator hole formed in the dielectric block and a multi-stage having three or more resonator holes formed therein. It is needless to say that the present invention can be applied to a dielectric filter, an antenna duplexer, etc. having a configuration.

FIG. 3 is an external perspective view of the trap filter. In this configuration, the trap capacitance Ce generated between the inner conductor 3 and the connection electrode 5 (input / output electrode) by tilting the inner conductor non-forming portion 6 is shown. (External coupling capacity) can be changed.

In the first and second embodiments, the input / output electrodes are formed on a part of the outer conductor. However, a so-called resin pin in which a metal terminal is embedded in resin without providing the input / output electrodes. May be inserted into the resonator hole for input / output.

Of course, the present invention can be applied to a dielectric filter in which another coupling means such as a stepped surface or a coupling groove is provided on the outer surface of the dielectric block.

[0031]

As described above, according to the dielectric filter of the present invention, the inner conductor non-forming portion provided in the vicinity of the opening surface of the resonator hole is formed with an inclination, and the inclination angle thereof is By changing the inclination direction, the coupling between the adjacent resonators and the external coupling can be easily adjusted and set to desired values without changing other configurations such as the external dimensions.

Therefore, it is possible to increase the degree of freedom in design, and it is possible to realize various and good filter characteristics with dielectric filters having the same shape.

[Brief description of drawings]

FIG. 1 is a sectional view of a dielectric filter according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a dielectric filter according to a second embodiment of the present invention.

FIG. 3 is an external perspective view of a dielectric filter (trap) according to another embodiment of the present invention.

FIG. 4A is an external perspective view of a conventional dielectric filter, and FIG. 4B is a sectional view thereof.

[Explanation of reference symbols] 1 dielectric block 2, 2a, 2b resonator hole 3 inner conductor 4 outer conductor 5 input / output electrode 6 inner conductor non-formation portion

Claims (1)

[Claims] 1. A resonator hole is provided in a dielectric block, an inner conductor is formed on an inner surface of the resonator hole, and an outer conductor is formed on an outer surface of the dielectric block, and at least one of the resonator holes is formed. In a dielectric filter having an inner conductor non-forming portion formed in the vicinity of the opening surface, the inner conductor non-forming portion is formed with a predetermined width over the entire circumference of the resonator hole, and A dielectric filter characterized by being formed so as to be inclined with respect to it.