JPH03252201A - Band attenuating filter - Google Patents

Abstract

PURPOSE:To obtain a small-sized and inexpensive band attenuating filter by forming auxiliary electrodes, between which and each inner conductor the capacitance is generated, on the surface of a dielectric resonator and connecting auxiliary electrodes with inductance elements among them. CONSTITUTION:Inner conductor leading-out electrodes 4a, 4b, and 4c led out from the open end part of an inner conductor and an outer conductor leading-out electrode 6 led out from an outer conductor 5 are formed on the open end face of the dielectric resonator. Auxiliary electrodes 7a, 7b, and 7c are formed in middle positions between the electrode 6 and electrodes 4a, 4b, and 4c. Therefore, the capacitance is generated among electrodes 7a, 7b, and 7c, electrodes 4a, 4b and 4c, and the electrode 6. Inductance elements L1 and L2 are connected among electrodes 7a, 7b, and 7c. A band filter having electrodes 7a and 7c as the input terminal and the output terminal is obtained. Thus, the number of parts is reduced and the production cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a bandpass attenuation filter using an integrated TEM mode dielectric resonator.

BACKGROUND ART Conventionally, for example, a combline type cavity resonator or a half-shaft type cavity resonator has been used as a reception filter for a duplexer. Furthermore, filters using TEM mode dielectric resonators are used for applications that require further miniaturization.

For example, a band attenuation filter using an integrated TEM mode dielectric resonator was invented (U.S. Pat. No. 4.823
．． No. 098).

The equivalent circuit of the above band attenuation filter is shown in FIG.
In the figure, DR1, DR2, and DR3 are TEM mode dielectric resonators, and SLI and SL2 are λ/4 strip lines patterned on the open end surfaces of the integrated TEM mode dielectric resonators, respectively. Also, C1, C2
, C3 is the inner conductor of each resonator and the strip line SLI,
This is a capacitor generated between SL2.

With the above configuration, the dielectric resonator DRI
, DR2, and DR3 have band attenuation characteristics having their respective resonance frequencies as attenuation poles.

(C) Problem to be Solved by the Invention However, in the above-mentioned band attenuation filter in which a λ/4 strip line is formed on the open end surface of the integrated TEM mode dielectric resonator, the entire dielectric resonator is made smaller. Indeed, the space between the open end faces becomes narrower, making it difficult to form a strip line with a length of λ/4. This becomes a factor that prevents miniaturization of a band attenuation filter made of an integrated TEM mode dielectric resonator.

An object of the present invention is to provide a smaller and cheaper band attenuation filter that does not require the formation of a λ/4 strip line on the open end face of an integrated TEM mode dielectric resonator.

(d) Means for Solving the Problems The band attenuation filter of the present invention comprises an integrated TEM mode dielectric resonator in which a plurality of inner conductors are provided inside a dielectric block and an outer conductor is formed on the outer surface, and a substrate. Auxiliary electrodes are formed on the surface or the surface of the dielectric resonator to generate capacitance between each of the inner conductors and the outer conductor, and these auxiliary electrodes are connected via an inductance element. It is characterized by

(e) Function In the band attenuation filter of the present invention, a plurality of inner conductors are provided inside the dielectric block, and an outer conductor is formed on the outer surface, thereby forming an integrated TEM mode dielectric resonator. The auxiliary electrodes provided on the surface of the dielectric resonator or the surface of a separately provided substrate generate capacitance between each inner conductor of the dielectric resonator and the auxiliary electrode, and between each auxiliary electrode and the outer conductor. Further, each auxiliary electrode is coupled by an inductance element.

An equivalent circuit diagram of the band attenuation filter having the above configuration is shown in FIG. In FIG. 2, DRl.

DR2 and DR3 are each TEM mode dielectric resonators and are configured in a single dielectric block. A capacitor C21 is formed between the inner conductor and the auxiliary electrode of the resonator DPI, and a capacitor C21 is formed between the auxiliary electrode and the outer conductor. Capacitors C12 and C22 are configured between the inner conductor and the auxiliary electrode of DR2, and between the auxiliary electrode and the outer conductor, respectively, and capacitors C12 and C22 are configured between the inner conductor and the auxiliary electrode of the resonator DR3, and between the auxiliary electrode and the outer conductor, respectively.
13 and C23 are constructed. And therefore, the resonator D
Band-pass attenuation filter characteristics having attenuation poles at the respective resonance frequencies of R1, DR2, and DR3 are obtained.

In addition, in this way, the λ/4 strip line is connected to inductance elements (Ll, L2, etc.) and capacitors (C11, C
21, C12, C22, C13゜C23, etc.), a band attenuation filter consisting of a smaller integrated TEM mode dielectric resonator with a shortened distance between each inner conductor is constructed. be able to.

(f) Embodiment FIG. 1 shows an external perspective view of a band attenuation filter according to a first embodiment of the present invention. In FIG. 1, l is a dielectric block whose entire shape is a substantially rectangular parallelepiped, and as shown in the figure, there are three through holes 2a, 2b, 2C penetrating between two opposing surfaces.
are formed at equal intervals. Inner conductors 3a3b and 3c are formed on the inner walls of these through holes, respectively. Further, an outer conductor 5 is formed on the four side surfaces and the bottom surface of the dielectric block 1, and the inner conductors 3a, 3b, and 3c are connected to the outer conductor 5 at the bottom surface. This acts as three TEM mode dielectric resonators with the top surface in the figure as an open end surface and the bottom surface as a short-circuited end surface. On the open end surface of the dielectric resonator,
an inner conductor extraction electrode 4a drawn out from the open end of the inner conductor;
4b and 4c are formed, respectively, to form an outer conductor lead-out electrode 6 drawn out from the outer conductor 5. Auxiliary electrodes 7a, 7b, and 7c are formed at intermediate positions between the outer conductor lead electrode 6 and the inner conductor lead electrodes 4a, 4b, and 4c, respectively. Therefore, the inner conductor extraction electrodes 4a, 4b, 4C and the auxiliary electrode 7
A predetermined pattern of electrodes is formed on each part of the dielectric block 1 such that capacitance is generated between each of a, 7b, and 7c, and a capacitance is also generated between each of the auxiliary electrodes 7a, 7b, and 7c and the outer conductor extraction electrode 6. After that, as shown in the figure, an inductance element L1 is connected between auxiliary electrodes 7a and 7b, and an inductance element L2 is connected between auxiliary electrodes 7b and 7c by soldering or the like.

With the above configuration, a band attenuation filter as shown in the equivalent circuit of FIG. 2 is constructed. Figures 1 and 2
The figures correspond to each other as follows. DPI is inner conductor 3a
, a TEM mode dielectric resonator consisting of an outer conductor 5 and a dielectric block 1. Signal input terminal IN is auxiliary electrode 7
a, C11 is a capacitor generated between the auxiliary electrode 7a and the outer conductor extraction electrode 6, and C21 is a capacitor generated between the auxiliary electrode 7a and the inner conductor extraction electrode 4a. Similarly DR2
is a TEM mode dielectric resonator consisting of an inner conductor 3b, an outer conductor 5 and a dielectric block l, C12 is a capacitor generated between the inner conductor extraction electrode 4b and the auxiliary electrode 7b, and C2
2 is a capacitor generated between the auxiliary electrode 7b and the outer conductor extraction electrode 6. Similarly, DR3 is a TEM mode dielectric resonator consisting of an inner conductor 3c, an outer conductor 5, and a dielectric block 1, C13 is a capacitor generated between the inner conductor extraction electrode 4c and the auxiliary electrode 7C, and C23 is a capacitor formed between the auxiliary electrode 7c and the outer conductor. This is a capacitor generated between the conductor lead electrodes 6. Moreover, as described above, this auxiliary electrode 7c becomes the output terminal OUT.
Even if the EM mode dielectric resonator itself becomes smaller, it is still possible to use an integrated TEM mode dielectric resonator by configuring the capacitance of the lumped constant circuit using the electrode pattern and by connecting an inductance element as the lumped constant circuit element. A band-pass attenuation filter can be constructed.

Next, a perspective view of the band attenuation filter according to the second embodiment □ is shown in FIG. 3. In FIG. It is a square hole that runs parallel to the . A ground electrode 9a9b continuous to the outer conductor 5 and the outer conductor extraction electrode 6 is formed on the inner walls of the two through holes 8a and 8b. The rest of the structure is the same as that shown in FIG. By providing a ground electrode between each resonator in this way, coupling between each resonator due to uneven strain capacitance or dielectric constant on the open end face of the resonator is completely prevented, thereby preventing deterioration of the damping characteristics. can do.

Next, FIG. 4 shows a perspective view of a band attenuation filter according to a third embodiment. In FIG. 4, 1 is a dielectric block, which has three through holes 2a for forming inner conductors as in the previous embodiment.
, 2b, 2c, and inner conductors 3a, 3b,
3c is formed. In addition, outer conductors 5 are formed on the four side surfaces and the bottom surface (rear side in the figure) of the dielectric block 1,
Inner conductors 3a, 3b, and 3c are connected to outer conductor 5 at the bottom surface. On one side (top surface in the figure) of each resonator, a part of the outer conductor 5 is separated near the open end surface to form auxiliary electrodes 7a, 7b, and 7c, respectively, with inner conductors 3a, 3b,
3c. Therefore, the inner conductors 3a, 3
b, 3c and the auxiliary electrodes 7a, 7b, 7c, respectively (C1l, C12 in the equivalent circuit of FIG.
, C13) occurs. In addition, auxiliary electrodes 7a, 7b, 7c
Capacitance (C21, C22, C23 in the equivalent circuit of FIG. 2) is generated between the outer conductor 5 and the outer conductor 5, respectively. By connecting an inductance element L1 between auxiliary electrodes 7a and 7b and an inductance element L2 between auxiliary electrodes 7b and 7c by soldering or the like, a band attenuation filter using auxiliary electrodes 7a and 70 as signal input/output terminals is constructed. configured.

Next, a perspective view of a band attenuation filter according to a fourth embodiment is shown in FIG. In FIG. 5, reference numeral 1 denotes a dielectric block having three through holes for forming inner conductors, and inner conductors 3a, 3b, and 3c are formed in the through holes, and four side and bottom surfaces of the dielectric block 1 (the rear in the figure) are formed. The outer conductor 5 is formed in the direction (direction). In this embodiment, auxiliary electrodes and the like are not formed on the surface of the dielectric resonator, but are provided on a separate substrate. In the figure, 10 is a dielectric substrate, and an inner conductor 3 a is provided on the surface of the dielectric substrate.
= 3 b + 3 c Inner conductor extraction electrodes 11a, llb, and llc are formed to draw out the open end portions.

Although shown schematically in the figure, these inner conductor extraction electrodes and the inner conductor are connected by connection terminals or the like.

A ground electrode 13 is further formed on the surface of the substrate 10,
This ground electrode 13 and inner conductor extraction electrodes 11a, llb,
Auxiliary electrodes 12a, 12b, and 12c are formed at intermediate positions of llc, respectively. Therefore, the inner conductor extraction electrode 11a,
11blie and the auxiliary electrodes 12a, 12b, and 12a, respectively.
1l, C12, C13) are generated. In addition, the auxiliary electrode 12
There are capacitances between a, l 2-e-, 12C and the earth electrode 13 (C21, C22, and
C23) occurs. An inductance element L1 is connected between the auxiliary electrodes 12a and 12b, and an inductance L2 is connected between the auxiliary electrodes 12b and 12a. In this way, a band attenuation filter is constructed in which the auxiliary electrodes 12a and 12c serve as signal input/output terminals.

In addition, in the embodiments shown above, filters having only band attenuation filter characteristics were used as examples, but the band attenuation filter of the present invention is configured in a part of the -type TEM mode dielectric resonator, and the band attenuation filter of the present invention is applied to other areas. It is also possible to use an integrated filter that includes a bandpass filter.

(g) Effects of the Invention According to the present invention, the number of components is smaller and the cost can be lowered compared to a device using a plurality of dielectric coaxial resonators. Furthermore, a smaller integrated TEM mode dielectric resonator can be used without being restricted by the λ/4 strip line, resulting in a smaller and cheaper band-attenuation filter.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a perspective view of a band attenuation filter according to a first embodiment of the present invention, and FIG. 2 is an equivalent view of a band attenuation filter according to the first to fourth embodiments of the present invention. It is a circuit diagram. 3, 4 and 5 are perspective views of band attenuation filters according to second, third and fourth embodiments of the invention. FIG. 6 is an equivalent circuit diagram of a conventional band attenuation filter. - dielectric block, a ~ 2C - through hole for forming inner conductor, a ~ 3C - inner conductor, a ~ 4c, lla ~ 1lc - inner conductor trigger pile electrode, one outer conductor, one outer conductor extraction electrode, a, 9b, 13a-earth electrode, a-7c, 12a-12c-auxiliary electrode, a, 9b-through hole for forming earth electrode, 〇-dielectric substrate. a Figure 1

Claims (1)

[Claims] (1) An integrated TEM mode dielectric resonator in which a plurality of inner conductors are provided inside a dielectric block and an outer conductor is formed on the outer surface, and each of the inner conductors is provided on the surface of the substrate or the surface of the dielectric resonator. A band attenuation filter characterized in that auxiliary electrodes are formed to generate capacitance between the auxiliary electrode and the outer conductor, and these auxiliary electrodes are connected via an inductance element.