JPH075681Y2 - Coaxial resonator bandpass filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an improvement of a bandpass filter used in a microwave band.

[Prior Art] Conventionally, a coaxial resonator band-pass filter used in a microwave band projects a plurality of coaxial resonators 3 facing a space inside a metal housing 1 as shown in FIG. The adjusting screw 4 screwed into the metal housing 1 is opposed to the coupling elements 2 for input / output coupling provided at both ends of the space. Then, by rotating the adjusting screw 4 to change the distance from the coupling element 2, the opposing capacitance is loaded to change the external Q and the variation in the mechanical manufacturing at the time of manufacturing is absorbed. .

[Problems to be solved by the device]

In the conventional coaxial resonator bandpass filter described above, in the high micro frequency band of X band or higher, it is necessary to reduce the facing dimension of the space in the metal housing 1 in order to increase the cutoff frequency. Therefore, in the external Q adjustment mechanism including the coupling element 2 and the adjusting screw 4, the facing capacitance between the open end of the coupling element 2 and the facing wall surface in the space of the metal housing 1 becomes large, and the adjustment by the adjusting screw 4 is very difficult. There was a problem of becoming.

It is an object of the present invention to provide a coaxial resonator bandpass filter which makes it possible to easily adjust the external Q with an adjusting screw while obtaining a desired cutoff frequency.

[Means for Solving the Problems]

The coaxial resonator band-pass filter of the present invention comprises coaxial resonators arranged side by side facing the internal space of a metal casing, coupling elements for input / output coupling arranged on both sides of the coaxial resonator, and the coupling element. And an adjusting screw screwed into the metal housing facing the open end of the coupling element, and further, a recess is formed in the inner wall of the internal space facing the open end of the coupling element to retract this part,
With this recess, the gap between the open end of the coupling element and the inner wall is increased to reduce the capacitance of the coupling element in this portion.

[Action]

In the above-mentioned configuration, by retracting the inner wall of the internal space facing the open end of the coupling element, even when the facing dimension of the internal space in the coaxial resonator is small, the open end of the coupling element and the facing inner wall of the internal space are The facing dimension is increased and the facing capacity is reduced to facilitate adjustment of the external Q by the adjusting screw.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

1 and 2 show an embodiment of the present invention. FIG. 1 is a front view and FIG. 2 is a sectional view.

In these figures, in the operating frequency band of the bandpass filter, the coaxial resonator 3 having one end open and the other end short-circuited is fixed so as to face the internal space of the metal casing 1 serving as a cutoff waveguide. Coupling elements 2 for input / output coupling are arranged at both ends of these coaxial resonators 3 arranged side by side at intervals. In the region where the coaxial resonators 3 are juxtaposed, the facing dimension a of the internal space is made relatively small according to the cutoff frequency. On the other hand, at the positions where the coupling elements 2 are arranged at both ends, a concave portion 1a is formed in the inner wall of the internal space facing the open end of the coupling element 2 and this portion is retracted, and the facing dimension b becomes as large as possible. I am trying. Then, an adjusting screw 4 is screwed into the retracted portion of the metal housing 1 so as to face the open end of the coupling element 2, and the tip position of the adjusting screw 4 is changed, whereby the coupling element 2 and The loading capacity between the two is variable.

In addition, as shown in FIG. 2, the width dimension c of the internal space of the metal housing 1 is set to the same dimension as before.

According to this configuration, the metal housing 1 in which the coaxial resonator 3 exists
By keeping the space size a of the internal space of 1 as small as before, it becomes possible to obtain a required cutoff frequency at a high frequency equal to or higher than the X band. On the other hand, in the coupling element 2, the facing capacitance can be reduced by increasing the facing dimension between the open end and the inner wall of the internal space, and the adjusting screw 4
It is possible to easily adjust the external Q by.

[Effect of device]

As described above, according to the present invention, since the inner wall of the internal space facing the open end of the coupling element is set back, the facing dimension of the internal space in the coaxial resonator is reduced to obtain the required cutoff frequency. There is an effect that the facing dimension between the open end of the coupling element and the facing inner wall of the internal space is increased, the facing capacitance is reduced, and the external Q can be easily adjusted by the adjusting screw.

[Brief description of drawings]

FIG. 1 is a front view of an embodiment of the present invention, FIG. 2 is a sectional view thereof, and FIG. 3 is a front view of a conventional structure. 1 ... Metal housing, 1a ... Recess, 2 ... Coupling element, 3 ...
Coaxial resonator, 4 ... Adjustment screw.

Claims (1)

[Scope of utility model registration request] 1. A coaxial resonator arranged side by side facing an internal space of a metal housing, coupling elements for input / output coupling arranged on both sides of the coaxial resonator, and the coupling element facing the open end of the coupling element. An adjusting screw screwed to the metal housing is provided, a recess is formed in the inner wall of the internal space facing the open end of the coupling element, and this portion is retracted, and this recess causes the open end of the coupling element and the A coaxial resonator bandpass filter characterized by increasing the facing distance to the inner wall to reduce the capacitance at the open end.