JPH0243801A - Structure of interdigital filter - Google Patents

Abstract

PURPOSE:To obtain high reliability and excellent mounting work performance by fitting each coupling rod to a guide groove formed on the upper face of a dielectric block at a prescribed interval to a corresponding resonance rod, adjusting the position and fixing the rod. CONSTITUTION:After the position of the coupling rods 21, 22 is adjusted with a prescribed interval to the corresponding rod 17 fitted to guide slots 23a, 24a of dielectric blocks 23, 24 respectively and fixed in the guide slots 23, 24 with an adhesives. Thus, while the coupling rods 21, 22 are floated electrically with respect to a case 11 via the dielectric blocks 23, 24, the rods are connected electrically stably to the electrode 15b of a circulator 15 or a signal input terminal pin 14 and while the coupling rods 21, 22 are positioned accurately with respect to the resonance rod 17, the rods are fixed stably in the case 11. Thus, the 4-7GHz band microwave interdigital filter with high reliability and excellent mounting work performance is obtained.

Description

[Detailed Description of the Invention] [Required] Regarding the structure of an interdigital filter suitable for use as a filter in the frequency band of 4 to 7 GHz, which is highly reliable and has good mounting workability for the 4 to 7 GHz band. The purpose of the present invention is to provide an interdigital filter structure, which consists of an elongated metal casing, two terminal pins for signal input and output that extend through the bottom wall near both longitudinal ends of the casing, respectively. , a circulator mounted on the inner surface of the bottom wall near one end of the casing and having one of its two electrodes connected to one terminal pin, and a circulator disposed at intervals in the longitudinal direction of the casing. An odd number of resonance rods are alternately attached to the inner surfaces of two opposing side walls, and two coupling rods are arranged inside the housing to face the resonance rods located near both ends of the housing. , two dielectric blocks fixed to the inner surface of the bottom wall of the casing to respectively support the coupling rods; It is fitted into the formed guide groove so that its position can be adjusted, and after the position adjustment, it is fixed in the guide groove, and one connecting rod is connected to the other electrode of the circulator via a conductive ribbon, and the connecting rod is attached to the other connecting rod. The other terminal pin is inserted into and connected to the conductor sleeve so that the conductor sleeve and the terminal pin can be flexibly deformed when adjusting the position of the coupling rod.

[Industrial application field]

The present invention relates to the structure of an interdigital filter used in microwave communication equipment.

[Prior Art and Problems to be Solved by the Invention] Conventionally, a combline filter combined with a circulator has been widely adopted as a distributed constant filter for the frequency 4 to 7 Gt (Z band) of microwave communication equipment. In some types of combline type filters, the coupling rod, which is placed opposite the resonant rod through a predetermined gap, can be directly fixed to the inner surface of the metal casing and electrically connected, so the mounting structure of the coupling rod is However, the combline type filter has the disadvantage that the passage loss of the microwave signal is large and the frequency-attenuation characteristics are asymmetrical with respect to the center frequency.

In order to reduce the passage loss of microwave signals and improve the symmetry of the frequency-attenuation characteristics with respect to the center frequency, it is desirable to use an interdigital type filter, but a highly reliable interdigital type filter combined with a circulator is recommended. In order to realize a filter, it is necessary to electrically stably connect the connecting rod to the signal input/output terminal bin or the electrode of the circulator while the connecting rod is floating electrically with respect to the casing. It is necessary to accurately position the coupling rod so that it faces the resonant rod at a predetermined distance, and to stably fix it within the housing. However, the reality is that an interdigital filter that satisfies these requirements has not yet been realized.

Therefore, an object of the present invention is to provide a structure of an interdigital filter for the 4 to 7 GHz band that is highly reliable and easy to implement.

[Means to solve the problem]

The interdigital filter according to the present invention includes an elongated metal casing, two terminal pins for signal input/output extending through the bottom wall near both longitudinal ends of the casing, and A circulator mounted on the inner surface of the bottom wall near one end and having one of the two electrodes connected to one terminal pin; An odd number of resonance rods are attached alternately to the inner surfaces of two side walls, and two coupling rods are arranged inside the housing so as to face the resonance rods located near both ends of the housing. two dielectric blocks fixed to the inner surface of the bottom wall portion and supporting coupling rods, and a guide formed on the upper surface of the dielectric blocks such that each coupling rod is spaced a predetermined distance from a corresponding resonance rod. It is fitted into the groove so that its position can be adjusted and is fixed in the guide groove after the position adjustment, one coupling rod is connected to the other electrode of the circulator via a conductor ribbon, and the above-mentioned coupling rod is connected to the conductor sleeve attached to the other coupling rod. The other terminal pin is inserted and connected so that the conductor sleeve and the terminal pin can be flexibly deformed when adjusting the position of the coupling rod.

[For production]

When assembling an interdigital filter having the above configuration, after fixing the dielectric block to the inner surface of the bottom wall of the casing, the connecting rod connected to the electrode of the circulator is inserted into the guide groove of one dielectric block. After adjusting the position so that it faces the side surface of the resonant rod attached to the inner surface of the side wall of the housing at a predetermined distance in the attached state, it is fixed in the guide groove with adhesive, etc., and then the conductor ribbon is Connect the coupling rod to the circulator electrode by soldering or the like. On the other hand, attach the coupling rod that connects to the input/output terminal bin to the guide groove of the other dielectric block, and insert the input/output terminal pin that passes through the bottom wall of the case into the conductor sleeve attached to the coupling rod. . Thereafter, the position of the coupling rod is adjusted within the guide groove so that it faces the side surface of the resonance rod attached to the inner surface of the side wall of the housing at a predetermined distance, and then fixed within the guide groove with adhesive or the like. With the method described above, it is possible to stably connect the coupling rod to the signal input/output terminal pin or the electrode of the circulator while it is electrically suspended from the housing via the dielectric block. In addition, the coupling rod can be stably fixed within the housing via the dielectric block while being accurately positioned relative to the resonant rod.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 to 5 show an embodiment in which the present invention is applied to a 6 GHz band filter. First, referring to FIGS. 1 and 2, the interdigital filter includes an elongated housing 11, and the housing 11 is made of a conductive metal such as aluminum. Near both ends in the longitudinal direction of the housing 11, two terminal pins 1 for signal input/output are provided, each extending through the bottom wall 12 of the housing 11.
3°14 is provided. As shown in detail in FIG. 5, the terminal pins 13.14 themselves are kept insulated from the bottom wall 12 of the housing 11, and the glass flange 13a is fixed to the terminal pins 13.14.

Conductor layers 13b and 14b made of cobalt-nickel alloy or the like provided on the outer periphery of 14a are connected and fixed to the bottom wall portion 12 of the housing 11 by soldering.

As shown in FIGS. 1 and 2, a MIC type circulator 15 is mounted on the inner surface of the bottom wall 12 near one end of the housing 11, and two electrodes 15a of the circulator 15 are mounted on the inner surface of the bottom wall 12 near one end of the housing 11.
, 15b is connected to one terminal pin 13 by soldering a conductive ribbon 160 of gold or the like.

Inside the casing 11, three resonance rods 17 extending in a direction parallel to the bottom wall 12 of the casing 11 and perpendicular to the longitudinal direction of the casing 11 are arranged at intervals in the longitudinal direction of the casing 11. One ends of the resonance rods 17 are alternately attached to the inner surfaces of two opposing side wall portions 19 and 20 of the housing 11 by screws 18, respectively.

Furthermore, within the housing 11 there are resonance rods 1 located near both ends of the housing 11.
Two connecting rods 21.7 facing each other.
22 is arranged, and a dielectric block 2 for supporting the coupling rods 21 and 22 is provided on the inner surface of the bottom wall portion 12 of the housing 11.
3.24 are fixed by screws 25. Note that an adhesive may be used when fixing the dielectric blocks 23 and 24 to the bottom wall portion 12 of the housing 11. The length 1 (FIG. 1) of the coupling rods 21, 22 is set to approximately 1/4 of the wavelength λ of the microwave signal to be passed.

Guide grooves 23a and 24a extending in the longitudinal direction of the housing 11 are formed on the upper surfaces of the dielectric blocks 23 and 24,
The coupling rods 21.22 are connected to dielectric blocks 23.24, respectively.
The guide grooves 23a and 24a are fitted in the guide grooves 23a and 24a so that the position can be adjusted, and the position is adjusted so as to be spaced from the corresponding resonance rod 17 by a predetermined distance D (FIG. 1). , 24a. Resonance rod 17
The spacing between the connecting rods 21 and 22 is determined within a tolerance range of ±0.1 mm depending on the center frequency of the microwave signal to be passed.

As shown in FIGS. 1, 2, and 4, the connecting rod 21 on the side connected to the circulator 15 is integrally provided with a tongue piece 21a that protrudes toward the circulator 15. The tongue portion 21a of 21 and the corresponding electrode 15b of the circulator 15 are connected via a conductor ribbon 26.

As shown in FIGS. 4 and 5, the other coupling rod 22 is formed with a mounting hole 22a that passes through it in the vertical direction, and a conductor sleeve 27 is inserted into this mounting hole 22a and fixed by soldering. has been done. The lower end of the conductor sleeve 27 protrudes below the coupling rod 22, and the conductor sleeve 27
A terminal pin 14 is inserted into and electrically connected. A plurality of slits 27a are formed in the conductor sleeve 27. The sleeve 27a plays the role of generating appropriate contact pressure between the conductor sleeve 27 and the terminal pin 14. The dielectric block 24 that supports the coupling rod 22 has a hole 24b vertically formed therethrough through which the conductor sleeve 27 and the terminal pin 14 are inserted. terminal pin 14
and has a sufficient inner diameter to allow the flexural deformation.

As can be seen from FIGS. 4 and 5, a total of seven adjustment screws 31 for adjusting the resonance frequency and for adjusting the degree of coupling are attached to the top cover 30, which is attached to the top surface of the housing 11 with a plurality of screws 29. .

When assembling an interdigital filter having the above configuration, after fixing the dielectric blocks 23 and 24 to the inner surface of the bottom wall 12 of the casing 11, the coupling rod 21 connected to the circulator 15 is attached to one dielectric block. After adjusting the position along the guide groove 23a with the connecting rod 23 installed in the guide groove 3a, the connecting rod 2 is fixed in the guide groove 3a with adhesive, and then the conductor ribbon 26 is soldered to the connecting rod 2.
1 is connected to the electrode 15b of the circulator 15. On the other hand, the coupling rod 22 connected to the input/output terminal pin 14 is attached to the guide groove 24a of the other dielectric block 24, and the terminal pin 14 is inserted into the conductor sleeve 27 attached to the coupling rod 24. After that, after adjusting the position of the connecting rod 22 along the guide groove 24a, the connecting rod 22 is attached to the guide groove 24a with adhesive.
It sticks inside. By the above method, the connecting rods 21 and 22
can be stably electrically connected to the signal input/output terminal pin 14 or the electrode 15b of the circulator 15 while electrically floating with respect to the housing 11 via the dielectric blocks 23 and 24, and the coupling The rods 21, 22 can be stably fixed in the housing II via the dielectric blocks 23, 24 while being accurately positioned relative to the resonant rod 17.

As the material for the dielectric blocks 23 and 24, it is desirable to use a styrene-based resin that has a dielectric constant comparable to that of polytetrafluoroethylene and can be used with an adhesive.

In addition, the dielectric block 2324 is attached to the bottom wall portion 12 of the housing 11.
The screws 25 for fixing to the dielectric blocks 23 and 24
It is preferable to use the same resin or polytetrafluoroethylene.

Although the illustrated embodiments have been described above, the present invention is not limited to the embodiments described above, and for example, the number of resonant rods can be changed depending on the bandwidth of the microwave to be passed. In addition, changes can be made to the connection and fixing methods of each component.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the connecting rod is electrically suspended from the housing via the dielectric block, and the signal input/output terminal pin or the electrode of the circulator is electrically connected to the connecting rod. In addition, the coupling rod can be stably fixed in the housing via the dielectric block with the coupling rod accurately positioned relative to the resonant rod, resulting in high reliability and ease of mounting work. Good 4~7Gt
(An interdigital type filter for Z-band microwaves can be provided.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the inside of the housing of an interdigital filter showing an embodiment of the present invention; FIG. 2 is a cross-sectional view of the embodiment shown in FIG. 1 taken along the line ■-■ in FIG. 3 is a side view of the embodiment shown in FIG. 1, FIG. 4 is an exploded perspective view of the embodiment shown in FIG. 1, and FIG. 5 is an enlarged sectional view of a main part of the embodiment shown in FIG. 1. In the figure, 11... Housing, 12... Bottom wall part, 13.14
...Terminal pin, 15...Circulator, 15a, 15b...Electrode, 17...Resonance rod, 19°21.22...Coupling rod, 23.24...Dielectric block, 23a, 24a... Guide groove, 26... Conductor ribbon, 27... Conductor sleeve. 20... side wall part,

Claims (1)

[Claims] 1. An elongated metal casing (11), two terminal pins (13, 14) for signal input/output extending through the bottom wall (12) near both longitudinal ends of the casing, and the casing. Two electrodes (15
a, 15b), one (15a) of which is connected to one terminal pin (13); An odd number of resonance rods (17) are alternately attached to the inner surface of the side walls (19, 20), and the resonance rods are arranged inside the housing so as to face the sides of the resonance rods located near both ends of the housing. Two connecting rods (21, 22) and two connecting rods each fixed to the inner surface of the bottom wall of the housing to support the connecting rods.
a resonant rod (17) to which each of the coupling rods (21, 22) corresponds;
Dielectric blocks (23,
24) Guide grooves (23a, 24a) formed on the top surface
The connecting rod (21) is fitted into the circulator (1) so that the position can be adjusted, and after adjusting the position, it is fixed in the guide groove.
5) is connected to the other electrode (15b) via a conductor ribbon (26), and the other terminal pin (14) is inserted and connected to the conductor sleeve (27) attached to the other coupling rod (22). A structure of an interdigital filter characterized in that the conductor sleeve (27) and the terminal pin (14) are formed so as to be able to bend and deform when adjusting the position of the coupling rod (22).