JPH04104501A - Dielectric filter - Google Patents

Abstract

PURPOSE:To correct the deviation of resonance frequency between input/output- side resonators and inter-stage resonators without damaging the sharpness of resonance and the mass productivity by making a space capacity near the input output resonators larger than a space capacity of the remaining dielectric resonators. CONSTITUTION:Plural dielectric resonators 16 are regularly arranged in the space closed with an enclosure 11 and a cover 12, and two dielectric resonators in both ends out of plural dielectric resonators 16 are coupled to input/output- side couplers 13 and 14 as input/output-side resonators, and adjusting screws 15 partially piercing the cover 12 are provided to face dielectric resonators 16 in 1:1. The capacity of the space around input/output-side resonators out of the space involving all of plural dielectric resonators 16 is made relatively larger than that around dielectric resonators except input/output-side resonators. Thus, the sharpness of resonance is improved, and this filter is superior in mass productivity and the cost is excellently reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dielectric filter, and particularly to a dielectric filter that selects the frequency of signals in the microwave band.

In recent years, dielectric filters using dielectric resonators have begun to be used in branching filters and the like of microwave band communication devices because of their small size and high performance. FIG. 4 is an external perspective view of an example of the dielectric filter, in which the dielectric filter 10 has a hollow interior housing 11.
A dielectric resonator is installed in a closed space inside the housing 11 with a lid 12, and the frequency of the microwave band introduced from the input coupler 13 is selected and extracted from the output coupler 14. In addition, 15 is a metal adjustment screw, which is attached to the housing 11.
They are provided in a dielectric resonator in a l-to-l ratio, and are provided to adjust the resonant frequency by adjusting the insertion length.

Dielectric filters with such a structure are designed to reduce costs and improve mass productivity.

[Conventional technology]

FIGS. 5(A) and 5(B) respectively show a plan view and a sectional view of various parts of a conventional dielectric filter. In the figure, the same components as in FIG. 4 are given the same reference numerals.

In FIGS. 5(A) and 5(B), five dielectric resonators 16 are supported by a support base 17 and arranged at regular intervals within the housing 11. Out of the five dielectric resonators 16, two dielectric resonators located at both left and right ends (hereinafter referred to as input/output resonators) are provided with an input coupler 1 spaced close to the outside thereof.
The metal rods 13a of No. 3 and the metal rods 14a of the output coupler 14 are arranged, respectively.

In the dielectric filter having such a configuration, the resonance frequencies of the five dielectric resonators 16 are made to differ slightly from each other, so that a reflection characteristic having a dip at the five resonance frequencies as shown by I in FIG. 6 is achieved. As a result, the configuration is such that it has a pass characteristic as shown in the figure, and the microwave band signal introduced into the input coupler 13 is given a bandpass filter characteristic and is taken out from the output coupler 14.

Here, each of the five dielectric resonators 16 is adjusted independently from each other by adjusting the insertion length of the adjustment screws 15 that are provided one-to-one opposed to each other.

In addition, increase the insertion length of the adjustment screw 15 to adjust the adjustment screw! When the tip of the dielectric resonator 6 is brought closer to the dielectric resonator 16, the resonant frequency changes to become higher.

[Problem to be solved by the invention]

However, in the conventional dielectric filter described above, each of the metal rods 13a and 14a of the input side coupler 13 and the output side coupler 14
are provided close to and spaced apart from the input and output side resonators due to necessity, whereas the remaining three dielectric resonators excluding the left and right ends of the five dielectric resonators 16 (hereinafter referred to as tiers) Since such a metal rod does not exist in the interstage resonator, the resonant frequency of the input/output resonator is higher than that of the interstage resonator.

For this reason, adjustment has conventionally been carried out by making the insertion length of the interstage resonator adjustment screw longer than the insertion length of the input/output side resonator adjustment screw. However, this method requires a long insertion length as the adjustment screw 15, and as the insertion length increases, the sharpness of the resonance of the corresponding dielectric resonator deteriorates. There is a problem with not being able to obtain the characteristics.

On the other hand, it is also possible to configure the input/output side resonators to have a resonant frequency set to a lower value than the interstage resonators, but in that case, two types of dielectric resonators 16 would be required, which would reduce the cost. There are also problems in terms of mass production.

The present invention has been made in view of the above points, and is a dielectric material that can correct the difference in resonance frequency between the input/output side resonator and the interstage resonator without impairing the sharpness of resonance or mass production. The purpose is to provide filters.

[Means to solve the problem]

The dielectric filter of the present invention is a space sealed by a housing and a lid, and a space capacitance near an input/output side resonator in a space in which a plurality of dielectric resonators are regularly arranged. is configured to be relatively larger than the spatial capacitance of the remaining dielectric resonators excluding the input/output side resonators.

[Effect]

As shown in FIG. 1, the dielectric resonator 22 supported by the support base 21 within the space 20 resonates at a resonant frequency corresponding to the capacitance of the space 20. Furthermore, when the space capacitance near the dielectric resonator 22 is increased by the capacitance of the space 23 in addition to the capacitance of the space 20, the resonant frequency of the dielectric resonator 22 is inversely proportional to the increased capacitance of the space 23. Change. That is,
The larger the spatial capacitance near the dielectric resonator 22, the lower the resonant frequency, and conversely, the smaller the spatial capacitance, the higher the resonant frequency.

The present invention focuses on the above principle, and by making the space capacitance near the input/output side resonator relatively larger than the space capacitance near the other interstage resonators, the input/output side resonator It is possible to correct the deviation from the resonant frequency of the interstage resonator, which is caused by the fact that the interstage resonator is provided close to the input/output side coupler, by keeping all the dielectric resonators in the same configuration. .

〔Example〕

FIG. 2 shows the configuration of each part of an embodiment of the present invention.

The external appearance of this embodiment is the same as that shown in FIG. 4, and the same components in FIG. 2 as in FIG. 5 are given the same reference numerals. 2(A) is a perspective view of the lid 30, FIG. 2(B) is a top view of the housing 11, and FIG. 2(C) is a sectional view of the dielectric filter of this embodiment.

As shown in FIGS. 2(A) and 2(C), this embodiment is characterized in that recesses 31 and 32 are provided in the portions of the lid 30 facing the input and output resonators, respectively, so that the inside of the housing 11 The configuration is the same as the conventional one, as shown in FIGS. 2(B) and 2(C), respectively.

Therefore, all the dielectric resonators 16 have the same configuration.

As can be seen from FIG. 2(C), in this embodiment, the space capacitance near the input/output side resonator increases compared to the space capacitance near the resonator between the dividing stages of the recess 31, so the input/output side The resonant frequency of the resonator is lower than that of the crotch resonator.

On the other hand, as described above, the metal rod 13a of the input/output side coupler 13, 14 is located close to the input/output side resonator.

14a, the resonant frequency of the input/output side resonator is shifted higher than that of the interstage resonator. Therefore, as a whole, the metal rods 13a, 1 of the input/output side resonator
The deviation of the resonant frequency in the high frequency direction due to the close arrangement of the resonators 4a is offset by the increase in the space capacity due to the recess 31, and the deviation from the resonant frequency of the interstage resonator can be corrected. Therefore, the insertion lengths of the five adjustment screws 15 are approximately equal, and unnecessary increases in insertion length can be suppressed, thereby preventing deterioration of resonance sharpness (Qo) due to an increase in insertion length. . In addition, since all the dielectric resonators 16 have the same configuration, it is possible to improve mass productivity and reduce costs compared to when a plurality of types of dielectric resonators are provided.

Next, other embodiments of the present invention will be described. FIG. 3 shows a sectional view of a main part of another embodiment of the present invention.

In the figure, the same components as those in FIG. 5 are denoted by the same reference numerals, and the explanation thereof will be omitted. The embodiment shown in FIG. 3 is different from conventional dielectric filters in that recesses 41 and 42 are formed only at the bottom of the housing 40 and around the support base of the input and output side resonators, respectively. be.

In this case as well, since the space capacitance near the input/output side resonators is larger than that of the interstage resonator, it has the same features as the embodiment shown in FIG. 2.

Note that the present invention is not limited to the above-described embodiments. For example, a convex portion is provided on each portion of the surface of the lid 12 facing the dielectric resonator' that faces the interstage resonator, and the area near the input/output side resonator is provided with a convex portion. The space capacitance near the interstage resonator may be made smaller than the space capacitance of the interstage resonator. Furthermore, it goes without saying that the number of dielectric resonators 16 is not limited to five.

[Effects of the Invention] As described above, according to the present invention, the deviation between the resonant frequency of the input/output side resonator and the resonant frequency of the interstage resonator can be corrected while keeping the insertion length of the adjustment screw approximately equal. Because you can
The sharpness of resonance can be improved compared to the conventional method, and all dielectric resonators have the same configuration, so different types of dielectric resonators are used for the input/output resonator and the interstage resonator. It has advantages such as superior mass productivity and cost reduction compared to the conventional method.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the principle of the present invention, Fig. 2 is an explanatory diagram of the configuration of each part of an embodiment of the invention, Fig. 3 is a sectional view of main parts of another embodiment of the invention, and Fig. 4 is a dielectric diagram. FIG. 5 is a diagram showing the configuration of each part of an example of a conventional dielectric filter, and FIG. 6 is a diagram showing an example of frequency characteristics of the dielectric filter. 2.30 is a lid, 3 is an input end coupler, 4 is an output side coupler, 5 is an adjustment screw, 6.22 is a dielectric resonator, 7.21 is a support base, 20.23 is a space, 31 32. 41.4 is shown. 2 is the concave part

Claims (1)

[Claims] A plurality of dielectric resonators (16) are regularly arranged in a space sealed by a housing (11) and a lid (12), and the plurality of dielectric resonators (16) are arranged regularly. ), the two dielectric resonators at both ends are used as input/output side resonators, and the input/output side coupler (13,
14) and the plurality of dielectric resonators (14).
6), wherein each of the plurality of dielectric resonators (16) is provided with an adjustment screw (15) that partially penetrates the lid (12) and faces one-to-one to each of the dielectric filters. Among all the included spaces, the space capacitance near the input/output side resonator is made relatively larger than the space capacitance near the remaining dielectric resonators excluding the input/output side resonator. Dielectric filter.