JP2006191379A - Coaxial bandpass filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coaxial bandpass filter capable of extremely easily controlling electromagnetic field coupling quantity due to a coupling loop and capable of remarkably improving operation efficiency. <P>SOLUTION: The inside of a case 11 is divided into two spaces through an inner wall 12, and center conductor 13a, 13b are arranged on the centers of respective spaces to constitute coaxial resonators 14a, 14b. A coupling window 17 is formed on the inner wall 12 and a coupling loop fitting screw hole 21 is formed on the case 11 located under the coupling window 17. A loop seating 22 on which the coupling loop 18 is previously set is screwed into the screw hole 21. When the loop seating 22 is inserted into the screw hole 21, the coupling loop 18 is inserted into the case 11 and located on the coupling window 17 part. The loop seating 22 can be rotated in the state inserted into the screw hole 21, and the quantity of an electromagnetic field which interlinks the coaxial resonators 14a, 14b with the coupling loop 18 can be changed by the rotation of the loop seating 22 to control electromagnetic filed coupling quantity between the coaxial resonators 14a, 14b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coaxial bandpass filter configured by connecting coaxial resonators in multiple stages.

  2. Description of the Related Art Conventionally, for example, a base station in a mobile radio such as a taxi radio has provided an antenna sharing device between a plurality of communication devices and an antenna, and shares one antenna with a plurality of channels having different frequencies. The antenna sharing device is composed of a plurality of bandpass filters. As this bandpass filter, for example, a multistage coaxial bandpass filter is used (see, for example, Patent Document 1).

  A conventional multistage coaxial bandpass filter is configured as shown in FIGS. FIG. 5 is a perspective view showing a cross section of the front side of a conventional coaxial bandpass filter, and a cross-sectional view seen from the front direction of FIG. In FIGS. 5 and 6, the case lid (the upper surface of the case) is removed and the frequency tuning rod provided on the case lid is omitted.

  5 and 6, reference numeral 11 denotes a metal case. The case 11 is divided into a plurality of internal walls 12 by an internal wall 12, in this example, two spaces, and a central conductor 13 a, 13 b is provided at the center of each space and coaxial The resonators 14a and 14b are formed. Input / output terminals 15a and 15b are provided on both sides of the case 11, and input / output loops 16a and 16b provided in the case 11 are connected to the input / output terminals 15a and 15b, respectively.

A coupling window 17 formed by a notch is provided in the inner wall 12 separating the coaxial resonators 14a and 14b, and the coaxial resonators 14a and 14b are electromagnetically coupled by an electromagnetic field leaking from the coupling window 17. It is like that. Further, a coupling loop 18 is provided in the coupling window 17, so that the electromagnetic coupling amount between the coaxial resonators 14a and 14b can be varied by an electromagnetic field interlinking the coupling loop 18, that is, The amount of electromagnetic field coupling between the coaxial resonators 14a and 14b can be adjusted by deforming the coupling loop 18 and changing the amount of electromagnetic fields interlinked.
Japanese Utility Model Publication No. 3-28562

  In the coaxial bandpass filter, it is necessary to change the coupling amount between the coaxial resonators 14a and 14b due to the difference in the pass frequency when adjusting the filter characteristics. The adjustment of the coupling amount is as described above. The coupling loop 18 is deformed to change the amount of electromagnetic fields that are linked.

  When adjusting the electromagnetic field coupling amount, conventionally, a hole is formed in the case 11, and the internal coupling loop 18 is deformed from the hole. However, this adjustment method cannot be adjusted while confirming the internal state, and fine adjustment is very difficult.

In addition, the reproducibility of adjustment is very low, and it is difficult to reproduce what has been adjusted once with another filter. Further, since the coupling loop 18 is deformed, if the adjustment is excessively performed, the coupling loop 18 may be damaged. Furthermore, when the coupling loop 18 is replaced, the coupling loop 18 is fixed to the inner surface of the case 11, and therefore, it is necessary to disassemble and replace the coupling loop 18 once.
As described above, the conventional coaxial bandpass filter has a problem that adjustment work and the like are very troublesome and work efficiency is poor.

  The present invention has been made to solve the above problems, and provides a coaxial bandpass filter that can adjust the amount of electromagnetic field coupling by a coupling loop very easily and can significantly improve the working efficiency. With the goal.

  The present invention relates to a coaxial bandpass filter configured by connecting coaxial resonators in multiple stages, a coupling loop mounting screw hole provided in a case portion corresponding to each stage, and screwed into the screw hole. A loop pedestal and a coupling loop supported by the loop pedestal so as to be positioned between the stages of the coaxial resonator, and by rotating the coupling loop together with the loop pedestal, between the coaxial resonators The amount of coupling is adjusted.

  According to the present invention, the amount of coupling between the coaxial resonators can be adjusted by rotating the coupling loop provided on the loop base, so that adjustment from the outside is easy and fine adjustment is possible. Can be efficiently performed in a short time. In addition, the reproducibility of the adjustment can be improved, and when the coupling loop is exchanged, it can be performed very easily without disassembling the filter.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a coaxial bandpass filter according to an embodiment of the present invention in a cross-sectional view of a front side of the coaxial bandpass filter before the coupling loop is mounted, and FIG. 2 is a perspective view showing a state after the coupling loop is mounted. FIG. 3 is a cross-sectional view of the coaxial bandpass filter as viewed from the front. In addition, in FIG. 1 thru | or FIG. 3, while omitting a case cover body (case upper surface), the frequency tuning rod provided in a case cover body is abbreviate | omitted and shown.

  1 to 3, reference numeral 11 denotes a metal case. The inside of the case 11 is divided into a plurality of, for example, two spaces by an inner wall 12, and central conductors 13a and 13b are provided at the centers of the spaces to form a coaxial resonator. 14a and 14b are constituted. The center conductors 13a and 13b are formed in a cylindrical shape, and a frequency tuning rod (not shown) is inserted into the center conductors 13a and 13b from above, and the resonance frequency is adjusted by the amount of insertion. The frequency tuning rod is attached to, for example, a case lid (not shown) covering the upper portion of the case 11 with a nut or the like so that the amount of insertion into the central conductors 13a and 13b can be adjusted by rotating from the outside. It has become.

  Further, input / output terminals 15a and 15b are provided on both sides of the case 11, and input / output loops 16a and 16b made of a conductive member provided in the case 11 are provided on the input and output terminals 15a and 15b, respectively. Connected. Each of the input / output loops 16 a and 16 b has one end connected to the input / output terminals 15 a and 15 b and the other end connected to the case 11.

  A coupling window 17 by a notch is provided in the inner wall 12 separating the coaxial resonators 14a and 14b, and the coaxial resonators 14a and 14b are electromagnetically coupled by an electromagnetic field leaking from the coupling window 17. It is like that. A screw hole 21 for attaching a coupling loop is provided in a portion of the case 11 located below the coupling window 17. The screw hole 21 is formed, for example, by raising a part of the case 11 upward, that is, in a cylindrical shape in the case inner direction. The screw hole 21 may be separately attached to the case 11. A loop base 22 made of a conductive member is screwed into the screw hole 21. A coupling loop 18 is attached to the loop base 22 in advance. 2 and 3, the coupling loop 18 is provided so as to be inserted into the case 11 and positioned at the coupling window 17 when the loop base 22 is inserted into the screw hole 21.

  The loop pedestal 22 can be rotated while being inserted into the screw hole 21, and the amount of the electromagnetic field that links the coupling loop 18 from the coaxial resonators 14 a and 14 b is changed by the rotation. The amount of electromagnetic field coupling between 14a and 14b can be adjusted.

The loop pedestal 22 is configured as shown in FIGS. 4 (a) and 4 (b) so that the position of the coupling loop 18 can be adjusted after being inserted into the screw hole 21 provided in the case 11 and then fixed. It has become. 4A is a cross-sectional view of the loop pedestal 22, and FIG. 4B is a bottom view of the loop pedestal 22, in which the coupling loop 18 is omitted.
The loop base 22 is formed in a cylindrical shape, and a screw groove 23 is formed on the outer periphery thereof. In addition, a slit 24 is formed in the loop base 22 from the center of the side part through the center part toward the opposite side part.

  Further, a through hole 25 is provided in the center of the lower surface of the loop base 22 up to the vicinity of the slit 24, and a screw hole 26 is provided through the slit 24 portion from the tip of the through hole 25. Then, by inserting a position fixing screw (not shown) into the screw hole 26 and tightening, the space between the upper and lower portions of the loop base 22 is narrowed with the slit 24 as the center, and the screw groove formed on the outer periphery. 23 is fixed in pressure contact with the screw hole 21 of the case 11. A groove 27 is provided on the lower surface of the loop base 22 so as to pass through the center. The groove 27 is for rotating the loop base 22 using a jig.

  According to the above embodiment, the amount of coupling between the coaxial resonators 14a and 14b can be adjusted by the rotation of the coupling loop 18 provided on the loop pedestal 22, so that adjustment from the outside is easy and fine adjustment is possible. Therefore, adjustment work can be performed efficiently in a short time. Further, by marking the loop pedestal 22 to indicate the position of the coupling loop 18, the position state of the inner coupling loop 18 can be easily known even from the outside. Can be improved. Further, when the coupling loop 18 is replaced, the loop base 22 can be easily removed from the case 11, and therefore, the filter can be replaced very easily without disassembling.

  In the above embodiment, a case where a two-stage coaxial bandpass filter is configured has been described. However, even a multistage configuration can be implemented in the same manner as in the above embodiment.

  Further, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage.

It is a perspective view before the coupling loop mounting | wearing which shows the front side of the coaxial type bandpass filter which concerns on one Embodiment of this invention, and shows it in cross section. In the same embodiment, it is a perspective view which shows the state which mounted | wore the coupling loop. It is sectional drawing which looked at the coaxial type bandpass filter concerning the embodiment from the front. (A) is sectional drawing which shows the detail of the loop base part in the embodiment, (b) is the bottom view. It is a perspective view which cuts and shows the front side of the conventional coaxial type | mold band pass filter. It is sectional drawing which looked at the conventional coaxial type bandpass filter from the front direction.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Case, 12 ... Internal wall, 13a, 13b ... Center conductor, 14a, 14b ... Coaxial resonator, 15a, 15b ... Input / output terminal, 16a, 16b ... Input / output loop, 17 ... Coupling window, 18 ... Coupling loop 21 ... Screw holes for attaching coupling loops, 22 ... Loop base, 23 ... Screw grooves, 24 ... Slits, 25 ... Through holes, 26 ... Screw holes, 27 ... Grooves.

Claims (1)

  In a coaxial bandpass filter configured by connecting coaxial resonators in multiple stages, a coupling loop mounting screw hole provided in a case portion corresponding to each stage, and a loop base screwed into the screw hole; A coupling loop supported by the loop pedestal so as to be positioned between the stages of the coaxial resonators, and by rotating the coupling loop together with the loop pedestal, a coupling amount between the coaxial resonators is increased. A coaxial bandpass filter characterized by adjusting.

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