JPS58171102A - Dielectric filter - Google Patents

Abstract

PURPOSE:To make the frequency adjustment unnecessary, to improve the reliability and to make the mass production possible, by inserting a metallic bar into a hole for resonator which is formed in a dielectric block and projecting this metallic bar by a length corresponding to the resonance frequency and fixing the metallic bar. CONSTITUTION:Plural holes 11 for resonator are provided in a dielectric block 1, and conductor films 2 and 3 are formed on the inside face of these holes 11 and all of the surface of the dielectric block 1 except the upper face and both end faces. A resonance metallic bar 9 is inserted into each of holes 11 for resonator, and this metallic bar is projected by a prescribed length on a basis of a calculated value and an experimental value corresponding to the resonance frequency, and in this state, the resonance metallic bar 9 is fixed close to the conductor film 2 with a solder, a conductive paste, or the like. This dielectric block 1 is stored in a case 5, and a cover 10 is attached to the case 5 after an exciting material 4 and an input/output plug 6 are connected.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to improvements in dielectric filters used in mobile radio equipment, etc., and particularly relates to a dielectric filter in which a metal rod is protruded and fixed to a hole constituting a resonator. It is.

(b) Prior art and problems Conventional dielectric filters used in mobile radios, especially in-vehicle radios, have holes forming a plurality of resonators at predetermined intervals in one dielectric block. FIG. 1 is a perspective view showing a partial cross section of a conventional dielectric filter in which the entire surface of the dielectric including the inner surface of the holes except for the top surface and both end surfaces is metallized. In the figure, l is a dielectric block made of a high dielectric material and has a plurality of resonator holes 11, 2 is a conductive film formed on the inner surface of the resonator holes 11, and 8 is the upper surface and both ends of the dielectric block l. 4 is an excitation body provided at both ends of the dielectric block l, 5 is a case made of metal etc. and houses the dielectric block l, and 6 is an input/output connector attached to the case 5. A plug 7 is a lid of the case, and a resonant frequency adjusting screw 8 corresponding to the resonator hole 11 of the dielectric block 1 is movably attached to the lid 7.

The conductive films 2 and 8 are coated with a viscous material such as (silver + glass) on the inner surface of the resonator hole 11 of the dielectric block 1 and the entire surface of the dielectric block 1 except for the top surface and both end surfaces, and then heated. After forming and storing in a case 75 and connecting the excitation body 4 and the input/output connector 6, a lid 7 equipped with a resonance frequency adjusting screw 8 is attached to the case 5.

In this way, the resonant frequency adjustment screw 8 is rotated to adjust to a predetermined frequency, and the adjustment screw 8 is fixed so as not to turn. However, mobile radio equipment (in-vehicle).

For portable use, etc.), the frequency adjustment screw 8 may vibrate,
If it moves even slightly in response to an impact, the opposing area between the resonator hole 11 and the adjusting screw 8 changes, causing problems such as fluctuations in the resonant frequency and deterioration of characteristics.

(c) Purpose of the Invention In view of the above-mentioned conventional problems, the present invention aims to provide a dielectric filter in which metal rods are inserted into resonator holes, and the lengths corresponding to the resonant frequencies are protruded and fixed, and no adjustment is required. That is.

(d) Structure of the Invention rJ1TIn order to achieve the above-mentioned object, the present invention provides a dielectric filter in which holes forming a plurality of resonators are formed in a dielectric block, in which the holes forming the resonators are open. This is achieved by attaching a protruding metal rod to the side.

(e) Embodiments of the Invention Examples of the dielectric filter according to the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a perspective view showing a cross section of a main part for explaining an embodiment of the present invention, and FIG. 3 is a diagram (8, 1 is a plan view, @ is a front view showing a cross section of the main parts, and the same parts as in the previous time are given the same reference numerals. 9 is a resonant metal rod made of metal such as copper, and 10 is a lid.

The dielectric block l is formed by a metallization method or the like in which the conductor films 2 and 3 are coated on the inner surface of the resonator hole 11 of the dielectric block l and the entire surface of the dielectric block l except for two faces and both end faces and heated. A resonant metal rod 9 is inserted into each of the resonator holes 11 as shown in FIG. 3, and Hl, H2, Ha
The dielectric block l, in which the resonant metal rod 9 is tightly fixed to the conductor film 2 by soldering or a conductive base plate, with H4 protruding, is housed in the case 5, and the exciter 4 and input/output connector 6 are connected to each other. After each connection is made, the lid 10 is attached to the case 5.

By fixing the resonant metal rod 9 in the resonator hole 11 based on calculated and experimental values in this way, the resonant frequency does not change due to vibrations, shocks, etc.

Although the dielectric filter of this embodiment has seven wavelengths, if a conductive film is also formed on the upper surface of the dielectric block l, it becomes a dielectric filter with seven wavelengths. Further, the number of resonator holes 11 is not limited to four, but may be plural.

(Effects of the Invention) As is clear from the above explanation, the dielectric filter according to the present invention can omit the frequency adjustment process using conventional frequency adjustment screws, etc., and also reduces vibration.

Since it is not affected by shocks, reliability can be expected to be improved, and it is suitable for mass production and is extremely advantageous when applied to in-vehicle wireless devices.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a partial cross section for explaining a conventional dielectric filter, FIG. 2 is a perspective view showing a partial cross section for explaining an embodiment of the dielectric filter according to the present invention, FIG. 3 is for explaining the dielectric block according to the present invention (
a) is a plan view, and (b) is a front view showing a cross section of the main parts. The plug, 7 and 10 are lids, 8 is a resonance frequency adjustment screw, 9Fi resonance metal rod, and 11 is a resonator hole, respectively. Figure 1 F Figure 3 Cα)

Claims (1)

[Claims] A dielectric fill in which holes constituting a plurality of resonators are formed in a dielectric block, characterized in that a metal rod of a predetermined length is protruded from the open side of the holes constituting the resonators. dielectric filter,