JPS586403B2 - Filter using coaxial resonator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filter using a coaxial resonator, and more particularly to a filter using a coaxial resonator having a structure that is meaningful for manufacturing.

Conventionally, there have been filters using a coaxial TEM resonator in which a dielectric material is present, and for the purpose of miniaturization, for example, a filter as described in Japanese Patent Application Laid-Open No. 52-96844 has been invented. The invention seeks to provide a filter with even higher performance.

That is, one object of the present invention is to provide a small filter.

Another object of the invention is to provide a filter with a simple structure.

Another object of the present invention is to provide a filter with good reproducibility, or in other words, a filter that can be produced faithfully to the design.

Another object of the invention is to provide a low cost filter.

In summary, this invention has dielectric properties. At least one coaxial TBM resonator is used, which is a coaxial TEM resonator placed between the outer conductors and has a terminal protruding from the open end surface on the inner conductor, and a dielectric member connecting the input end and the output end is used. The filter is formed by providing at least one or more electrodes at intervals and connecting the terminals to the electrodes.

The above objects and other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

FIG. 1 shows an example of a resonator used in the embodiment filter,
In FIG. 1, 1 is an IA wavelength coaxial TEM resonator, and a dielectric material 4 such as a titanium oxide ceramic dielectric material is present between an inner conductor 2 and an outer conductor 3. The inner conductor 2 and the outer conductor 3 are bonded to the inner conductor 2 and the outer conductor 3 by baking a material, such as silver paste, which has excellent high-frequency conductivity and good adhesion to the dielectric material, onto the inner wall surface and outer peripheral surface of the thick pipe-shaped dielectric material 4. do.

The inside of the inner conductor 2 is hollow, and a coaxially long center rod 5 made of a similar ceramic or the like is fitted and fixed therein.
Both end faces are covered with electrode films 6 and 7 that are integrated with the inner conductor 2.

A terminal 8 is bonded to the electrode film 6 or 7 (in the illustrated example, to the electrode wire 6).

FIG. 2 shows another IA wavelength coaxial TEM resonator 9, in which the same parts as in the previous figure are given the same numbers and their explanation will be omitted.

The center rod 10 made of a dielectric material has an axial length longer than the dielectric material 4, and its protruding end side is covered with an electrode film 11 formed integrally with the inner conductor 2.

The center rod 10 may be entirely replaced with a metal rod.

FIG. 3 shows yet another quarter-wavelength coaxial TEM resonator 12, . The same parts as those in the previous figure are given the same numbers and their explanation will be omitted.

Reference numeral 13 denotes a terminal electrode made of a metal rod, which is fitted into a hole surrounded by the inner conductor 2 and fixed thereto to be electrically and mechanically connected to the inner conductor 2.

The terminal electrode 13 may be formed by forming an electrode film on a dielectric material.

In the filter of the present invention, the above-mentioned resonator, that is, a dielectric material is used inside the filter. A coaxial TEM resonator is used, which is a coaxial TEM resonator placed between outer conductors, and a co-end TEM resonator in which an inner conductor is provided with a terminal protruding from an open end surface.

FIG. 4 shows an example 15 of the filter of the present invention. The same parts as those in the previous figure are given the same numbers and their explanation will be omitted.

The main case 16 is a rectangular rectangular body made of a conductor, for example duralumin, with holes 17, 18, 19, and 20 cut out therein.

Four resonators, for example, resonator 1, are fitted into the holes 17, 18, 19, and 20, respectively, and the outer conductor 3 of the resonator 1 is inserted into the case 1.
6 so as to be electrically conductive.

This fixing is performed, for example, by using a conductive adhesive or by screwing.

21 is an input coaxial connector, and 22 is an output coaxial connector, which are provided in the main case 16.

The center conductors 23, 24 of each connector 21, 22 are connected by one dielectric rod 25 made of, for example, ceramic porcelain.

More specifically, terminal electrodes 26 and 27 are provided at both ends of the dielectric rod 25, respectively, and coupling electrodes 28, 29, 30, and 31 are provided at intervals.

Both electrodes are formed by baking silver paste.

The dielectric rod 25 provided with electrodes in this way is connected to the hole 17.1.
Hole 32 between holes 8 and 19, hole 33 between holes 18 and 19, holes 19 and 20
It is inserted through the hole 34 between them.

The center conductor 23 and the terminal electrode 26 are connected, and the coupling electrode 28 and the terminal 8 of the first stage resonator 1 are connected.

The coupling electrode 29 and the terminal 8 of the second stage resonator 1 are connected.

The coupling electrode 30 and the terminal 8 of the third stage resonator 1 are connected.

The coupling electrode 31 and the terminal 8 of the fourth stage resonator 1 are connected.

Then, the terminal electrode 21 and the center conductor 24 are connected.

The specific connection structure is shown in Figures 4 and 5 as well as Figure 6.
This is more clearly disclosed in FIG.

That is, the terminal 8 is provided with a groove 35 having a semicircular cross section or a hole 36.

Of course, the invention is not limited to these two examples. The degree of coupling between the resonators 1 is determined by each length 1 of the coupling electrodes 28 to 31.

The capacitance (effective capacitance) between mutually adjacent coupling electrodes i and j is Ci
When j is the element, fo is the element of the original low-pass filter, fo is the center frequency, and Δf is the bandwidth.

An equivalent circuit of this embodiment filter is shown in FIG.

The effective capacitance can be changed by the stray capacitance Cs shown by a dotted line in the figure.

Therefore, the coupling coefficient can be controlled by the stray capacitance Os.

To change the stray capacity Cs, holes 32, 33, 3
The electrode 37 is provided on the dielectric rod 25 by changing the diameter of the hole 4 or by baking silver paste.

In addition, 38 is an upper pig case.

The main case 16 and the upper case 38 are not limited to metal, and may be made of, for example, plastic with a shielding effect.

As is clear from the above embodiments, according to the present invention, a dielectric material is used internally. At least one coaxial TEM resonator exists between the outer conductors and the inner conductor has a terminal protruding from the open end surface, and a dielectric member connects the input end and the output end. Since at least one or more electrodes are provided at intervals between the filters and the terminals are connected to the electrodes, it is possible to provide a filter that is φ-shaped, has a simple structure, and can easily be manufactured as designed and at a low cost.

Although the illustrated embodiment has been described with respect to a filter inserted into a coaxial line, the present invention can of course be applied to a waveguide or a strip line by adding an appropriate conversion circuit configuration.

[Brief explanation of the drawing]

1 to 3 are sectional views of a resonator used in the present invention, FIG. 4 is a sectional view of an embodiment of the filter of the present invention, and FIG. 5 is a sectional view of a resonator used in the present invention.
Same, plan view with the upper lid case removed, Figures 6 and 7
The figure is a sectional view taken along the line A--A in FIG. 5, and FIG. 8 is an equivalent circuit diagram of an embodiment of the filter of the present invention. 4 is a dielectric, 2 is an inner conductor, 3 is an outer conductor, 1, 9, and 12 are 1/4 wavelength coaxial TEM resonators, 8 is a terminal, 11 is an electrode film, 13 is a terminal electrode, 21 is an input coaxial connector , 22 is an output coaxial connector, 25 is a dielectric rod, 28, 29, 3
0 and 31 are coupling electrodes.

Claims (1)

[Claims] 1 A coaxial TEM resonator in which a dielectric material is present between the inner and outer conductors, and at least one coaxial TEM resonator in which the inner conductor is provided with a terminal protruding from the open end surface is used, and the input end, A filter in which at least one or more electrodes are provided at intervals on a dielectric member connecting output ends, and the terminals are connected to the electrodes.