JPS6333902A - dielectric filter - Google Patents

Abstract

PURPOSE:To obtain a stable filter characteristic having a flat temperature characteristic by adding a capacitor correcting the temperature characteristic in parallel with respect to the temperature coefficient of a dielectric coaxial resonator in use, the temperature coefficient of a coupling capacitor and the difference from the temperature coefficient due to the difference in the band width of the filter manufactured. CONSTITUTION:An inner conductor 12a and an outer conductor 12b are formed to the dielectric coaxial resonator 12 and an inner electrode 14 and an outer electrode 15 in continuity respectively with the inner conductor 12a and the outer conductor 12b are formed to an open end face 13. In arranging the rear side of the dielectric 7 to the open end face 13 of the resonator 12, the outer electrode 15 of the resonator 12, a 3rd electrode of the dielectric 7, and the inner electrode 14 of the dielectric coaxial resonator 12 and a 2nd electrode 10 of the dielectric 7 are connected and conducted and soldered or stuck by a conductive resin or the like. A lead metallic fixture 16 has a positioning tongue 17 fitted to the dielectric 7 and a connection piece 18 to be connected to the coupling capacitor 19, the positioning tongue 17 is inserted to a hole 9 of the dielectric 7 and connected by soldering or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a dielectric filter using a dielectric coaxial resonator used in various electronic devices.

Prior Art A conventional dielectric filter will be explained with reference to FIG.

The dielectric coaxial resonator 1 is made of a dielectric cylinder, and one end surface other than the open end surface, the outer peripheral surface, and the entire inner peripheral surface are coated with silver metallization. A center fitting 2 made of metal is inserted into the inner periphery of the dielectric coaxial resonator 1, and is attached by soldering or the like. The coupling capacitor 3 is made of a dielectric substrate, and the surface thereof is provided with an electrode for forming a coupling capacitance by silver metallization. Dielectric coaxial resonator 1 is a coupling capacitor 3
A center fitting 2 is inserted into a hole provided in the center of the capacitor 2 and connected to a coupling capacitor 3 by soldering. Similarly, the input/output terminals 4 are inserted into holes at both ends of the coupling capacitor 3 and soldered. The case 5 made of metal has the entire ground terminal 6, and is configured to be fixed to the outer circumferential conductor of the dielectric coaxial resonator 1 by soldering or the like.

Problems to be Solved by the Invention In the structure described above, the temperature characteristics of the dielectric filter are determined by the temperature coefficient of the coupling capacitance of the dielectric coaxial resonator 1 and the coupling capacitor 3. The increase and decrease of the coupling capacitance depending on the band also affects the temperature characteristics of the dielectric filter, making it difficult to obtain the ideal flat temperature characteristics.

The present invention eliminates the above-mentioned conventional drawbacks, and aims to provide a dielectric filter with flat temperature characteristics.

Means for Solving the Problems In order to solve the above problems, the dielectric filter of the present invention has a dielectric material provided with an electrode for forming a temperature compensation capacitance on the open end surface of a dielectric coaxial resonator. , the capacitance is added in parallel by connecting the dielectric electrodes to the outer circumferential conductor and inner circumferential conductor of the dielectric coaxial resonator.

° Effect: With this technical means, the temperature characteristics of the dielectric filter are temperature-corrected by the dielectric having a temperature coefficient that requires correction, and stable filter characteristics with flat temperature characteristics are obtained.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, FIGS. 1 to 3.

In Figure 2, B, a dielectric 7 made of a dielectric substrate with excellent high frequency characteristics and a required temperature coefficient has a hole 9 in the center, and a first electrode 8 is formed on almost the entire surface. and a circular second electrode 1o including a hole 9 in the center on the back surface;
A third electrode 11 is formed at a distance from and around the second electrode 10 . The second electrode 1o is electrically connected to the first electrode 8 through a hole 9 in the center of the dielectric 7 through a through hole.

In FIG. 1, a dielectric coaxial resonator 12 made of a dielectric rectangular cylinder has silver metallization applied to one end surface other than the open end surface, the entire outer circumferential surface, and the entire inner circumferential surface to form an inner circumferential conductor 121L and an outer circumferential conductor 12b. The open end surface 13 is provided with an inner electrode 1 that is electrically connected to the inner circumferential conductor 121L and the outer circumferential conductor 12b, respectively.
4. An outer electrode 16 is formed. Dielectric coaxial resonator 1
By arranging the back surface of the dielectric 7 on the open end surface 13 of the dielectric 7, the outer electrode 15 of the dielectric coaxial resonator 12, the third electrode 11 of the dielectric 7, and the inner electrode 14 of the dielectric coaxial resonator 12 can be connected to each other. It is brought into electrical contact with the second electrode 1o of the dielectric 7 and fixed by soldering or conductive resin. Lead metal fittings 16 made of metal
has a positioning tongue piece 17 for mounting on the dielectric body 7 and a connecting piece 18 for connecting it to the coupling capacitor 19, inserting the positioning tongue piece 17 into the hole 9 of the dielectric body 7, and soldering it etc. ) will be connected.

FIG. 3 shows a two-stage dielectric filter constructed using the dielectric coaxial resonator having the above structure.

The coupling capacitor 19 is made of a dielectric substrate with excellent high frequency characteristics such as alumina, has holes for inserting the lead fittings 16 and the input/output terminals 20, and has silver metallization on the surface of the substrate to form a coupling capacitance. electrodes are applied. The input/output terminals 20 are made of metal processed by flattening or the like, and solder or the like is applied thereto. The lead fittings 16 and the input/output terminals 20 of the string electrocoaxial resonator 12 configured as described above are inserted into the holes of the coupling capacitor 19 and soldered. The case 21 is made of metal plated with solder, etc., and is fixed to the outer circumferential conductor 12b of the dielectric coaxial resonator 12 by soldering.

Effects of the Invention As described above, according to the present invention, temperature characteristics can be improved with respect to differences in temperature coefficient due to differences in the temperature coefficient of the dielectric coaxial resonator used, the temperature coefficient of the coupling capacitor, and the bandwidth of the manufactured filter. By adding a correction capacitor in parallel, stable filter characteristics with flat temperature characteristics can be obtained.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is an exploded perspective view of the main parts of a dielectric filter according to an embodiment of the present invention, Fig. 2 is a top view and a bottom view of a dielectric filter according to an embodiment of the present invention. 3 shows a partially cutaway side view of a dielectric filter according to an embodiment of the present invention, and FIG. 4 shows a partially cutaway side view of a dielectric filter according to a conventional example. Completed...Dielectric, 8...First electrode, 9.
...hole, 1°...second electrode, 11...
...Third electrode, 12...Dielectric coaxial resonator,
13...Open end surface, 14...Inner electrode,
15... Outer electrode, 16... Lead fitting. Name of agent: Patent attorney Toshio Nakao and 1 other person7-
Ritsu 1 electric 1 tea 3--one curse 1 electric" 丞U-one part 3 electrodes/2b

Claims (1)

[Claims] The open end surface of the λ/4 dielectric coaxial resonator has an inner conductor,
An inner electrode and an outer electrode are provided that are electrically connected to the outer conductor, respectively.
A plate-shaped dielectric with a hole in the center has a first electrode on its front surface and a second electrode electrically connected to the first electrode through a through-hole on its back surface.
A third electrode is applied to the electrode and a periphery separated from the electrode, the back surface of the dielectric is arranged on the open end surface of the dielectric coaxial resonator, and the inner circumferential conductor of the dielectric coaxial resonator, the second electrode of the dielectric, and the dielectric A dielectric filter in which a capacitance is added in parallel to the dielectric coaxial resonator by connecting the outer circumferential conductor of the body coaxial resonator and a dielectric third electrode, and a lead metal fitting is drawn out from the dielectric first electrode.