JPS637682B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dielectric filter, and more particularly to a dielectric filter that takes measures to achieve miniaturization and improved productivity.

A bandpass filter of a high frequency circuit used in a mobile radio device, particularly a vehicle-mounted radio device, is composed of a circuit in which a plurality of resonators are arranged in parallel. One such filter is a dielectric filter, in which a plurality of holes are provided in parallel at a predetermined interval in one dielectric block, and the entire surface including the holes except for the top surface and a pair of both side surfaces of the dielectric is FIG. 1 shows a conventional dielectric filter which is metallized and further has holes for adjusting the degree of coupling between adjacent holes. In the figure, a is a plan view with the lid removed, and b is a cross-sectional view of main parts from the front. 1 is made of a high dielectric material, and each hole 11 is set to a predetermined resonance frequency and constitutes a resonator; Hole 12 for adjusting the degree of coupling between each resonator
2 is a conductive film formed on the inner surface of the resonator hole 11; 3 is the upper surface of the dielectric block 1 and a pair of both side surfaces and the hole 12;
4 is an input/output conductor film provided on both non-metalized sides of the dielectric block 1, 5 is a case made of metal etc. and houses the dielectric block 1; 6 is a case made of metal, etc.; A high-frequency electric signal input/output connector 7 is a lid of the case 5, and adjustment screws 8 and coupling degree adjustment threaded rods 9 corresponding to holes 11 and 12 of the dielectric block 1 are screwed into the lid 7, respectively. A fixing lock nut 81 is attached to the adjusting screw 8 and the adjusting screw rod 9, respectively.
and 91 are attached. The conductor films 2, 3, and 4 are formed, for example, by a metallization method in which a viscous material of silver and glass is applied and then heated. Further, the input/output conductor film 4 provided on the dielectric block 1 and the input/output connector 6 are connected by conductors, respectively. Rotate the resonant frequency adjusting screws 8 and the coupling degree adjusting threaded rods 9 corresponding to the holes 11 and 12 of the dielectric block 1, respectively, to adjust the resonant frequency of the resonator to a predetermined resonant frequency, and After adjusting the degree of coupling between the resonators, the fixing lock nuts 81 and 91 are tightened and fixed. However, it is well known that there is a strong demand for mobile radio devices (vehicle-mounted, portable, etc.) to be small and lightweight;
and 91, there were problems in that the dielectric filter itself had to be made smaller, including the protrusion of the threaded portion, and that many parts and time were required for production.

An object of the present invention is to improve the above-mentioned problems, and focuses on using metal rods of different lengths as the resonance frequency adjusting means. Briefly stated, the present invention consists of holes constituting a plurality of resonators at predetermined intervals in the longitudinal direction of a dielectric block, and a plurality of coupling adjustment holes parallel to the holes constituting the resonators separated by a predetermined distance. A hole is provided between the holes constituting the resonator, and a conductive film is applied to the entire surface of the dielectric block except for the upper surface and both side surfaces of the dielectric block, the hole constituting the resonator, and the hole for adjusting the degree of coupling. , metal rods of different lengths having a predetermined resonance frequency are inserted into the holes constituting the resonator, and the end surfaces of the metal rods are connected to the dielectric block between the opposing conductor surfaces. and are arranged at predetermined intervals, respectively, and a counterbore is formed in the screw hole corresponding to the coupling degree adjusting hole of the dielectric block of the case lid. Embodiments of the dielectric filter according to the present invention will be described in detail below with reference to the drawings.

In FIG. 2, a is a plan view and b is a sectional view of main parts from the front for explaining one embodiment of the present invention, and parts equivalent to those in the previous figure are designated by the same reference numerals. 2
0 is a dielectric block 21 made of a high dielectric material and having holes 201 for forming a plurality of resonators similar to those shown in FIG. 1 and holes 202 for adjusting the degree of coupling between the respective resonators. 22a to 22f are conductive films formed on the entire surface of the dielectric block 20 except for the upper surface, the pair of side surfaces, and the holes 201 and 202, that is, the bottom surface and the other pair of side surfaces, and 22a to 22f constitute a resonator in a coaxial mode. Metal rods of different lengths are inserted into the holes 201 and are determined to have a predetermined resonance frequency. 23 is the lid of the case 5, and the lid 23 has metal rods inserted into the holes 202 for adjusting the degree of coupling of the dielectric block 20. A counterbore 231 is formed at a corresponding position to a screw hole for the adjustment screw rod 24 and on the outside, and the screw rod 24 is screwed into the hole. The above configuration has six holes 201,
The holes 202 are provided at five locations, and the length of the hole 201 constitutes a resonator with a quarter wavelength.

Further, conductive films 4 and 21 are formed on parts of the other pair of both side surfaces that are not metalized. The conductor film 21
and 4 are formed by, for example, a metallization method in which a viscous material of silver and glass is applied and then heated.

The dielectric block 20 is housed in a metal case 5,
The conductor film 4 for input/output coupling and the input/output connector 6 are respectively connected.

The metal rods 22a to 22f are inserted into the holes 201, and one end (lower end) is in contact with the conductive film 21 on the metallized bottom surface of the dielectric block 20. The upper end protrudes from the unmetallized upper surface of the dielectric block 20 and is located in the space between the lid 23 and the upper surface of the dielectric block 20. These metal rods 22a to 22f
is inside the dielectric block 20 and the outer periphery in contact with the inner surface of the hole 201 constitutes the inner conductor of the coaxial mode resonator for the dielectric and the outer metallized layer.
The resonance frequency of each resonator can be minutely changed by changing the capacitance between the end faces determined depending on the facing distance of the lid 23.

Therefore, if the desired resonator and resonant frequency cannot be obtained due to manufacturing errors in the dielectric block 20, dimensional differences in the case 5, etc., the overall resonator and resonant frequency will be high (or low). The heights of the protruding ends of the metal rods 22a to 22f, that is, the distances _L1 ... _L6 relative to the lid 23, are determined to compensate for the deviation of the resonant frequency. This can be appropriately selected based on the actual measurement value, or can be determined to obtain the required frequency. Of course, it would be sufficient to replace it with a metal rod of such length, and after it has been determined, fix it with an appropriate adhesive or the like.

The threaded rod 24 for adjusting the degree of connection is screwed onto the lid 23,
The head is buried in the counterbore 231. The tip of the threaded rod 24 is connected to the hole 202 for adjusting the coupling degree of the dielectric block 20.
Since the length of insertion is determined in advance to a predetermined length, it is sufficient to fix the length by tightening the screws.If there is a difference in the degree of connection, move the screw slightly or use a longer screw. Set the position of the rod to achieve the desired degree of connection, and replace it with a screw of a length that matches that length. In this manner, the head of the coupling degree adjusting threaded rod 24 enters into the counterbore 231 formed in the lid 23, so that there is no protrusion to the upper surface of the lid 23.

Note that if any of the metal rods 22a to 22f is lower than the height of the dielectric block, the inner surface of the hole may be made of a conductive film (metallized) instead of the metal rod. Furthermore, although six resonator holes have been described, the number of resonator holes may be any number depending on the purpose of use. The portion of the coupling degree adjusting threaded rod 24 inserted into the hole 202 may be a simple rod.

As is clear from the above description, the dielectric block according to the present invention is a dielectric filter that is small and lightweight, has fewer adjustment parts, and has a reduced number of parts, resulting in excellent productivity, and is applicable to various mobile radio devices, etc. This is extremely advantageous.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a conventional dielectric filter with the lid removed; FIG. 2 is a sectional view of main parts from the front; FIG. 2 is an illustration of an embodiment of a dielectric filter according to the present invention. A is a plan view, and b is a sectional view of main parts from the front. In the figure, 1 and 20 are dielectric blocks;
2, 3, 4 and 21 are conductor films, 5 is a case, 6
are input/output connectors, 7 and 23 are lids, 8 are resonance frequency adjustment screws, 9 and 24 are threaded rods for coupling degree adjustment, 11 and 201 are holes, 12 and 20
2 is a hole for adjusting the coupling degree, 22a to 22f are metal rods,
81 and 91 are fixing nuts, and 231 is a counterbore.

Claims (1)

[Claims] 1. A plurality of holes constituting a plurality of resonators are arranged at predetermined intervals in the longitudinal direction of the dielectric block, and a plurality of coupling adjustment holes parallel to the holes constituting the resonators are arranged at a predetermined distance from each other in the resonator. A conductor film is provided on the entire surface of the dielectric block except for the upper surface and the pair of side surfaces, the hole forming the resonator, and the hole for adjusting the degree of coupling, thereby forming the resonator. Metal rods of different lengths having a resonant frequency of a predetermined value are inserted into the holes, and the end surfaces of the metal rods are spaced from the conductor surface at a predetermined distance between the opposite conductor surfaces facing the dielectric block. 1. A dielectric filter characterized in that a counterbore is formed in a screw hole corresponding to a coupling degree adjustment hole of the dielectric block in the lid of the case.