JPH0795641B2 - Structure of interdigital filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The structure of an interdigital filter suitable for use as a filter in the frequency band of 4 to 7 GHz, and an interdigital filter for the 4 to 7 GHz band, which is highly reliable and has good mounting workability. For the purpose of providing the above structure, a long and slender metal housing, two terminal pins for signal input / output extending respectively through bottom walls near both ends in the longitudinal direction of the housing, and a housing A circulator that is mounted on the inner surface of the bottom wall near one end and has one of two electrodes connected to one terminal pin, and a circulator that is spaced apart in the longitudinal direction inside the housing and faces the housing 2 An odd number of resonance rods that are alternately attached to the inner surfaces of the two side wall portions, two coupling rods that are arranged in the housing so as to face the resonance rods that are located near both ends of the housing, and Solid inside bottom wall And two dielectric blocks that respectively support the coupling rods, and the position of the coupling rods can be adjusted in the guide groove formed on the upper surface of the dielectric block so that the coupling rods are spaced from the corresponding resonance rods by a predetermined distance. Fitted and fixed in the guide groove after position adjustment, one coupling rod is connected to the other electrode of the circulator via the conductor ribbon, and the other terminal pin is inserted into the conductor sleeve attached to the other coupling rod. The conductor sleeve and the terminal pin are connected so that they can be flexibly deformed when the position of the coupling rod is adjusted.

[Industrial application field]

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

[Problems to be Solved by Prior Art and Invention]

Conventionally, a comb line type filter combined with a circulator has been widely adopted as a distributed constant filter for a frequency band of 4 to 7 GHz of a microwave communication device. In this type of comb-line type filter, the coupling rod, which is arranged to face the resonance rod through a predetermined gap, can be directly fixed to the inner surface of the metal housing and electrically connected.
Although the mounting structure of the coupling rod is simple, the comb-line type filter has a drawback that a microwave signal has a large passage loss and the frequency-attenuation characteristic is asymmetric with respect to the center frequency.

In order to reduce the passage loss of the microwave signal and improve the symmetry of the frequency-attenuation characteristic with respect to the center frequency, it is desirable to use an interdigital filter, but a highly reliable interdigital filter combined with a circulator is recommended. In order to realize a shape filter, it is necessary to electrically connect the coupling rod to the signal input / output terminal pin or the electrode of the circulator in a state where the coupling rod is electrically floated with respect to the housing. It is necessary to accurately position the coupling rod so as to face the resonance rod at a predetermined distance and to stably fix the coupling rod in the housing. However, the reality is that an interdigital filter satisfying such requirements has not been realized yet.

Therefore, an object of the present invention is to provide a structure of an interdigital filter for the 4 to 7 GHz band which is highly reliable and has good mounting workability.

[Means for Solving the Problems] An interdigital filter according to the present invention is a signal input / output unit that extends through an elongated metal casing and a bottom wall portion near both ends in the longitudinal direction of the casing. Two terminal pins, a circulator mounted on the inner surface of the bottom wall near one end of the housing and one of the two electrodes being connected to one terminal pin, and arranged in the housing with a space in the longitudinal direction. Are arranged in the housing so as to face the odd-numbered resonance rods alternately attached to the inner surfaces of the two side wall portions of the housing that face each other and the resonance rods located near both ends of the housing. Two coupling rods and two dielectric blocks fixed to the inner surface of the bottom wall of the housing and supporting the coupling rods respectively are provided, and the coupling rods are spaced apart from the corresponding resonance rods by a predetermined distance. Formed on the upper surface of the body block The guide sleeve is fitted in the guide groove so that it can be adjusted in position, and is fixed in the guide groove after the position adjustment.One coupling rod is connected to the other electrode of the circulator via the conductor ribbon, and the conductor sleeve mounted on the other coupling rod. The other terminal pin is inserted and connected to the conductor sleeve and the terminal pin so that the conductor sleeve and the terminal pin can be flexibly deformed when the position of the coupling rod is adjusted.

[Action]

When assembling the interdigital filter having the above configuration, after the dielectric block is fixed to the inner surface of the bottom wall of the housing, the connecting rod connected to the circulator electrode is mounted in the guide groove of one dielectric block. After adjusting the position 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 interval, fix it in the guide groove with an adhesive or the like, and then solder the conductor ribbon. The connecting rod is connected to the electrode of the circulator by attaching or the like. On the other hand, the coupling rod on the side connected to the input / output terminal pin is mounted in the guide groove of the other dielectric block, and the input / output terminal pin penetrating the bottom wall of the housing is inserted into the conductor sleeve mounted on the coupling rod. . After that, the position of the coupling rod is adjusted in the guide groove so as to face the side surface of the resonance rod mounted on the inner surface of the side wall portion of the housing with a predetermined interval, and then the coupling rod is fixed in the guide groove with an adhesive or the like. With the method described above, the coupling rod can be electrically and stably connected to the signal input / output terminal pin or the circulator electrode while being electrically floated to the housing through the dielectric block. It is possible to stably fix the coupling rod in the housing through the dielectric block in a state where the coupling rod is accurately positioned with respect to the resonance rod.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 show an embodiment in which the present invention is applied to a 6 GHz band filter. Introduction First
Referring to FIG. 2 and FIG. 2, the interdigital filter is provided with a slender elongated housing 11, which is made of a conductive metal such as aluminum. Two terminal pins 13 and 14 for signal input / output extending through the respective bottom wall portions 12 are provided near both ends in the longitudinal direction of the housing 11. As shown in detail in FIG. 5, the terminal pins 13 and 14 themselves are kept insulated from the bottom wall 12 of the housing 11, and the glass flanges 13a and 14a fixed to the terminal pins 13 and 14 are Conductor layers 13b, 14 made of cobalt-nickel alloy or the like provided on the outer periphery
b is 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 portion 12 near one end of the housing 11, and one of the two electrodes 15a and 15b of the circulator 15 is mounted. Is connected to one terminal pin 13 by soldering a conductor ribbon 16 of gold or the like.

In the housing 11, three resonance rods 17 extending in a direction parallel to the bottom wall portion 12 of the housing 11 and orthogonal to the longitudinal direction of the housing 11 are arranged at intervals in the longitudinal direction of the housing 11. One end of the resonance rod 17 is alternately attached to the inner surfaces of the two side wall portions 19 and 20 of the housing 11 which face each other by screws 18 respectively.

Further, in the housing 11, two coupling rods 21 and 22 facing the side surfaces of the resonance rod 17 located near both ends thereof are arranged, and on the inner surface of the bottom wall portion 12 of the housing 11. Is a connecting rod 21,2
Dielectric blocks 23 and 24 for supporting 2 are fixed by screws 25. The dielectric blocks 23 and 24 are attached to the housing 1
An adhesive may be used when fixing to the bottom wall portion 12 of 1. The length l (FIG. 1) of the coupling rods 21 and 22 is set to be about 1/4 of the wavelength λ of the microwave signal to be passed.

Guide grooves 23a, 24a extending in the longitudinal direction of the housing 11 are formed on the upper surfaces of the dielectric blocks 23, 24, and the coupling rods 21, 22 are located in the guide grooves 23a, 24a of the dielectric blocks 23, 24, respectively. It is adjustably fitted and adjusted in position so as to separate a predetermined distance D (FIG. 1) from the corresponding resonance rod 17, and then fixed in the guide grooves 23a, 24a with an adhesive (not shown). . The distance D between the resonance rod 17 and the coupling rods 21, 22 is set 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 portion 21a protruding toward the circulator 15 side. Tongue 21a of 21 and corresponding electrode 15b of circulator 15
And 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 penetrating 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 has a connecting rod 22.
Of the terminal pin 14 on the conductor sleeve 27.
Is inserted and electrically connected. Conductor sleeve 27
A plurality of slits 27a are formed in the slit. Sleeve 2
7a plays a role of generating an appropriate contact pressure between the conductor sleeve 27 and the terminal pin 14. A hole 24b for inserting the conductor sleeve 27 and the terminal pin 14 is formed through the dielectric block 24 supporting the coupling rod 22 in the vertical direction.
When adjusting the position of the connecting rod 22,
And 14 have an inner diameter sufficient to flex and deform.

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

When assembling the interdigital filter having the above structure, the dielectric block is formed on the inner surface of the bottom wall 12 of the housing 11.
After fixing 23, 24, the coupling rod 21 on the side connected to the circulator 15 is adjusted along the guide groove 23a in a state of being mounted in the guide groove 23a of the one dielectric block 23,
It is fixed in the guide groove 23a with an adhesive, and then the conductor ribbon 2
The connecting rod 21 is connected to the electrode 15b of the circulator 15 by soldering 6. On the other hand, the coupling rod 22 on the side connected to the input / output terminal pin 14 is the guide groove 24 of the other dielectric block 24.
The terminal pin 14 is inserted into the conductor sleeve 27 attached to the connecting rod 24. After that, after adjusting the position of the connecting rod 22 along the guide groove 24a, the connecting rod 22 is fixed with an adhesive.
Stick inside. As described above, the coupling rods 21 and 22 are electrically floated with respect to the housing 11 via the dielectric blocks 23 and 24 and electrically connected to the signal input / output terminal pin 14 or the electrode 15b of the circulator 15. Of the housing 11 through the dielectric blocks 23 and 24 in a state where the coupling rods 21 and 22 are accurately positioned with respect to the resonance rod 17.
It can be stably fixed inside.

As the material of the dielectric blocks 23, 24, it is desirable to use a styrene resin whose dielectric constant is about the same as that of polytetrafluoroethylene and which can be used as an adhesive. Further, the screws 25 for fixing the dielectric blocks 23, 24 to the bottom wall portion 12 of the housing 11 are preferably formed of the same resin as the dielectric blocks 23, 24 or polytetrafluoroethylene or the like.

Although the illustrated embodiment has been described above, the present invention is not limited to the embodiment described above, and for example, the number of resonance rods can be changed according to the bandwidth of the microwave to be passed. Further, it is possible to change the connection and fixing method of each component.

〔The invention's effect〕

As apparent from the above description, according to the present invention, the coupling rod is electrically floated with respect to the housing via the dielectric block and electrically connected to the signal input / output terminal pin or the circulator electrode. The connection is stable, and the coupling rod can be stably fixed in the housing through the dielectric block in a state where the coupling rod is accurately positioned with respect to the resonance rod. Therefore, the reliability is high and the mounting workability is good. 4-7GHz
An interdigital filter for band microwave can be provided.

[Brief description of drawings]

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 sectional view taken along the line II-II in FIG. 1 of the embodiment shown 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 cross-sectional view of the essential part of the embodiment shown in FIG. In the figure, 11 ... Housing, 12 ... Bottom wall portion, 13, 14 ... Terminal pin, 15 ... Circulator, 15a, 15b ... Electrode, 17 ... Resonance rod, 19, 20 ... Side wall portion, 21, 22 ... Coupling rod, 23 , 24 ... Dielectric block, 23a, 24a
… Guide groove, 26… Conductor ribbon, 27… Conductor sleeve.

Continuation of the front page (56) References JP-A-49-4462 (JP, A) Actual development 61-21103 (JP, U) FUJITSU, Vol. 19, No. 6, PP. 144-165 (1968)

Claims (1)

[Claims] 1. A thin metal housing (11) and two terminal pins (13, 13) for signal input / output extending respectively through a bottom wall (12) near both ends in the longitudinal direction of the housing. 14) and two electrodes (15a, 15a, mounted on the inner surface of the bottom wall near one end of the housing).
A circulator (15), one of which (15a) of 15b) is connected to one of the terminal pins (13), and two side wall portions of the housing, which are spaced apart in the longitudinal direction in the housing and face each other. An odd number of resonance rods (17) alternately attached to the inner surface of (19, 20) and two resonance rods (17) arranged in the casing so as to face the side faces of the resonance rods located near both ends of the casing. The coupling rods (21, 22) and two dielectric blocks (23, 2) fixed to the inner surface of the bottom wall of the housing and supporting the coupling rods, respectively.
4) and a guide groove (23a, 23a formed on the upper surface of the dielectric block (23, 24) so that the coupling rods (21, 22) are spaced from the corresponding resonance rods (17) by a predetermined distance. 24a) is positionally adjustable and fixed in the guide groove after position adjustment. One connecting rod (21) is connected to the other electrode (15) of the circulator (15).
b) 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) to connect the conductor sleeve (27) and the terminal. An interdigital filter structure, characterized in that the pin (14) and the pin (14) are formed so that they can be flexibly deformed when the position of the coupling rod (22) is adjusted.