JPH03212002A - Dielectric filter - Google Patents

Abstract

PURPOSE:To make the size of a dielectric filter small without deteriorating its performance by providing two strip line filters arranged respectively onto the circumferential face of a 1st stage resonator and a final stage resonator of plural stages of waveguide type dielectric filters, and coupled respectively with the 1st stage resonator and the final stage resonator. CONSTITUTION:A coupling hole 8 is provided to a dielectric block 1 of prism shape and conductor metallize 2 is applied to the entire surface to form 3 stages of waveguide type dielectric filters. Then conductor patterns 61, 62 forming two strip line filters are arranged on the circumferential face of a 1st stage resonator and the final stage resonator of the 3 stages of waveguide type dielectric filters and the 1st stage resonator and the final stage resonator are coupled with them respectively. Thus, the length in the guide axis direction is reduced without deteriorating the characteristic of the waveguide type dielectric filter and miniaturization is attained.

Description

[Detailed Description of the Invention] Summary Regarding dielectric filters, we have developed a multi-stage waveguide type dielectric filter and a multi-stage waveguide type dielectric filter for the purpose of reducing the size of the dielectric filter without deteriorating its performance. , two slots l-'J arranged on the circumferential surfaces of the first-stage resonator and the final-stage resonator of the multi-stage waveguide dielectric filter and coupled to the first-stage resonator and the final-stage resonator, respectively. A tube line filter is provided.

[Industrial application field]

The present invention relates to a dielectric filter.

As a filter in the microwave band, it is necessary to miniaturize the device,
Although dielectric filters are widely used to improve performance, there is a demand for the development of dielectric filters that are smaller in size, have higher performance, and are easier to manufacture.

[Conventional technology]

As a microwave band band filter, a λ/4 resonant coaxial filter is generally used. FIG. 3 is a diagram showing an example of a five-stage λ/4 resonant coaxial filter.

Conductive metallization 2 is applied to five surfaces of the rectangular parallelepiped dielectric block 1 except for the top surface by baking etc., and the dielectric block 1 is
have coupling holes 4□-44 and resonant conductors 31-3. which are holes whose inner surfaces are conductor metallized. 5)
Ru.

5) In this type of filter; five resonant conductors 31
A five-stage coaxial bandpass filter with a resonance wavelength of λg is formed by resonance of the TEM mode centered around .about.35. Mutual coupling between the stages is generally said to be based on magnetic field coupling, and its size is adjusted by the sizes of the coupling holes 41-44. The microwave is supplied from a terminal that is capacitively coupled to the resonant conductor 31 at the farthest end, and taken out from a terminal that is easily coupled to the resonant conductor 35 at the other end.

Japanese Patent Laid-Open No. 63-220603 describes a waveguide type dielectric filter that has a simpler structure than this coaxial type filter, has a higher Q value than this coaxial type filter, has a simpler structure, and is easier to manufacture. body filter is described. Fourth
The figure shows an example of a five-stage filter.

A rectangular parallelepiped dielectric block 1 has a conductive metallization 2 applied over almost the entire surface thereof.

Pairs of through holes are provided at equal intervals in the axial direction, and conductor metallization is also applied to the inner surface of the through holes to form four pairs of coupling holes 8. The dielectric 1 is exposed in a concave shape at both end faces in the axial direction, and a microwave input end and an output end are formed, respectively.

The five areas separated by the four pairs of coupling holes 8 are each T.
A resonant circuit of the E 1o + mode is formed, and the strength of mutual coupling is adjusted by the size of the coupling hole 8 .

[Problem to be solved by the invention]

However, even in this waveguide type filter, for example, when configuring a 5-stage filter with a center frequency of 2 GHz using a high dielectric constant ceramic with ε = 90, the length in the tube axis direction is about 65 mm. As the miniaturization of devices progresses rapidly, such dimensional restrictions are becoming a major obstacle.

Therefore, an object of the present invention is to reduce the size of a dielectric filter without deteriorating its performance.

[Means to solve the problem]

The dielectric filter according to the present invention includes a plurality of stages of waveguide type dielectric filters, each arranged on the circumferential surface of a first stage resonator and a last stage resonator of the plurality of stages of waveguide type dielectric filters, 2 coupled with the first-stage resonator and the final-stage resonator, respectively.
The present invention is characterized by comprising two strip line filters.

In a waveguide type dielectric filter consisting of multiple stages, the contribution of the Q value of the first stage resonator and last stage resonator to the Q value of the whole filter is small, so even if these are replaced with a strip line filter, The characteristics do not deteriorate that much.

By placing this stripline filter on the circumferential surface of the waveguide resonator, the length in the tube axis direction is determined by the length of the waveguide filter, and is shortened by the amount replaced by the stripline filter. will be done.

The degree of coupling between the strip line filter and the waveguide filter can be adjusted by adjusting the position and size of the coupling hole, and further by inserting a metal rod there.

〔Example〕

FIG. 1 is a diagram showing a first embodiment of a dielectric filter according to the present invention. (a) shows a perspective view thereof, (b) shows a sectional view taken at the center in the tube axis direction, and (C) shows a XX sectional view.

A three-stage waveguide type dielectric filter is formed by providing coupling holes 8 in a rectangular parallelepiped dielectric block 1 and applying conductor metallization 2 to the entire surface.

The outer conductors in the central parts of the first and final stage resonators, that is, in the vicinity where the electric field strength is high (see column (C)), are removed in a circular shape as shown in 111 and 112. I
a conductor pattern 6 for forming a J-tube line filter;
and 6□, respectively, and coupling holes 101 and 102 of the strip line filter and a circularly removed portion 11 of the outer conductor described above are provided on one of the peripheral surfaces of the first stage and the last stage of the waveguide filter. and 112 respectively match,
The back ground conductor and the outer conductor of the waveguide filter are joined by soldering. The stripline filter may not be provided with a back ground conductor and may be joined by adhesive or the like. Alternatively, without providing a coupling hole, a portion of the ground conductor on the back surface of the substrate may be removed to match the outer conductor removed portion of the waveguide filter, and a coupling electrode pattern may be formed on the surface of the substrate! 7)
(not shown). The degree of coupling between the strip line filter and the waveguide filter can be adjusted by adjusting the position and size of the holes, inserting a metal rod (not shown), etc., depending on desired characteristics. The strip line filter may be multistage, and may be of the half-wavelength side coupling type shown in Fig. 1 or of the half-wavelength series coupling type.

FIG. 2 is a diagram showing a second embodiment of the present invention. In this example, two S/J tube line filters are formed on one dielectric substrate 53, and by connecting them with a conductor pattern 13, a shunt is provided between them to form a polarized circuit. By doing so, an attenuation pole is provided outside the passband. Of course, any of the resonators of the waveguide filter may be coupled using a similar structure.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to shorten the length in the tube axis direction without significantly deteriorating the characteristics of a waveguide type dielectric filter, and it is possible to significantly downsize the waveguide type dielectric filter. Become.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a first embodiment of a dielectric filter according to the present invention, Fig. 2 is a diagram showing a second embodiment of a dielectric filter according to the present invention, and Fig. 3 is a diagram showing a coaxial type filter. FIG. 4 is a diagram showing an example of a waveguide filter. In the figure, 1... IT body double block 2... Conductor metallization, 3
1 to 35... Resonant conductor, 4□ to 44... Coupling hole, 5, to 53... Dielectric substrate, 6□ to 6゜... Conductor pattern, End... Coupling hole, lO, ,10211,~11□
...Outer conductor removal section. ...joining hole,

Claims (1)

[Claims] 1. A plurality of stages of waveguide type dielectric filters (1, 2, 8), and on the circumferential surface of the first stage resonator and last stage resonator of the plurality of stages of waveguide type dielectric filters (1, 2, 8). 2 which are respectively arranged in and coupled to the first stage resonator and the final stage resonator, respectively.
A dielectric filter comprising two stripline filters (6_1, 6_2).