JPH0490201A - Waveguide type filter - Google Patents

Abstract

PURPOSE:To make the resonance frequency broad by providing plural filter elements to a slit provided orthogonal in a guide axis direction in a rectangular waveguide and varying the interval between a length of each filter element and the slit. CONSTITUTION:Signals of four frequency bands f1, f2, f3, f4 (f1>f2>f3>f4) are made incident on the waveguide filter from a rectangular waveguide and plural filter elements 3a-3d' are provided to a slit 2 orthogonal to the guide axis of the rectangular waveguide 1. The filter elements 3a, 3c are selected to have lengths D1a, D2a and an interval D3a with respect to the slit 2, then act like an LC resonance circuit with respect to the frequency band f2. Moreover, the filter elements 3b, 3d are selected to have lengths D1b, D2b, then act like an LC resonance circuit with respect to the frequency band f3. Thus, the slit 2 acts like a short-circuit plane with respect to frequency bands f2, f3 and pass other frequency bands without giving any effect and acts like a broad band stop filter.

Description

[Detailed description of the invention] [Industrial application field] Ko (7) Invention i:! , relates to a waveguide filter used as a filter element for microwave bands and millimeter wave bands.

U Prior Art] FIG. 6 is a perspective view of a conventional waveguide filter, FIG. 7 is an external view of a slit, and FIG. 8 is a diagram showing a filter element replaced with an equivalent circuit.

In the figure, (1) is a rectangular waveguide, (2) is a slit provided perpendicular to the tube axis of the rectangular waveguide, (3) is a filter element provided in the slit, and (4) is a waveguide. The capacitor C+, (S) between the waveguide filter and the slit has an actance r that corresponds to the path of the current flowing through the waveguide filter.
,,, (e) is the reactance 1. that the slit exhibits without the waveguide filter. t, (7) is the resistance R between the slots.

Next, the operation will be explained. When three frequency bands of f l+ f and f are incident on a conventional waveguide filter from a rectangular waveguide (1), here f,>ft>f
Assume that , .

When the filter elements (3a to 3d) are provided in the slit (2) provided perpendicularly to the tube axis in the rectangular waveguide (1), the length D of each part of each filter element (3a to 3d) Poem! and the distance between the filter element (3a to 3d) and the slit (2), the capacitor CI (4) and the reactance L, (5), and (2).

(6) is determined. Here D I+ D , and D
By setting 3 to a desired value, the filter element becomes a 7C resonant circuit only for the frequency band f. Therefore, the slit (2) and the filter elements (3a to 3c) act as short-circuit surfaces for the frequency band f, without any effect on the black vinegar frequency band fl'+f. [Problem to be Solved by the Invention] The conventional waveguide filter is configured as described above, so the length of the filter element beam and the distance between the slit and the slit are Since D3 is constant, there is a problem in that it is difficult to widen the resonance frequency.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to obtain a waveguide filter that makes it possible to widen the resonant frequency.

Means for Solving Problem 1 (1) The waveguide filter according to the present invention includes a plurality of filter elements provided in a slit provided in a rectangular waveguide so as to be orthogonal to the tube axis direction, and each filter It is constructed by changing the length of the element and the distance between it and the slot.

(2) The waveguide type filter according to the present invention has a plurality of filter elements arranged in a row on two opposing sides of a slit provided perpendicularly to the tube axis direction in a rectangular waveguide, and further provided on each side. The filter element is constructed by changing the length of the filter element.

[Function] (1) This waveguide type filter has a plurality of filter elements in the slits provided perpendicularly to the tube axis direction in the seven rectangular waveguides, and furthermore, the length of each filter element and the relationship with the slots are determined. By changing the spacing, it is possible to change and set the resonant frequency band of each filter element, and therefore it is possible to realize a waveguide filter with a wide resonant frequency band.

(2) This waveguide type filter has a filter element provided on two sides opposite to a slit provided perpendicularly to the tube axis direction in a rectangular waveguide, and furthermore, the length of the filter element provided on each side is By changing the spacing between the slits, it is possible to change and set the resonant frequency bands of the opposing filter elements, thereby realizing a waveguide filter with a wide resonant frequency band.

[Embodiment 1] Hereinafter, an embodiment of the present invention will be explained with reference to the drawings. Fig. 1 is a perspective view of an embodiment of a waveguide filter according to the present invention.
FIG. 2 is an external view of the slit, FIG. 3 is a diagram showing the filter element replaced with an equivalent circuit, FIG. 4 is a perspective view of a waveguide filter according to another embodiment of the present invention, and FIG. 5 is a diagram showing the filter element replaced with an equivalent circuit. FIG. 3 is a diagram showing the appearance of a slit.

In the figure, (1) is a rectangular waveguide, (2) is a slit provided perpendicular to the tube axis of the rectangular waveguide (1), and (3) is a rectangular waveguide.
is the filter element provided in the slit (2), (4) is the capacitor C between the waveguide filter and the slit, and (5) is the actance T corresponding to the path of the current flowing through the waveguide filter. , (6) is the reactance T that the slit exhibits without a waveguide filter, ? (7) is the resistance R between the slits.

(1) Next, the operation of the waveguide filter according to the present invention will be explained.

In FIG. 4, when four frequency bands f I+ f't+ f and f4 are incident on the waveguide filter from the rectangular waveguide (1), here f, > f, > f, > f
Assume that it is 4.

A plurality of filter elements (3a to 3d) are provided in a slit (2) provided perpendicularly to the tube axis in the rectangular waveguide (1). Here, filter elements (3a) and (3c
) is the length, a and I), 6 and the distance D from the slit.
By deciding that □.

The filter element has a capacitor CI(4) and reactances +-+(S) and T, (6) determined to have desired values. Therefore, filter elements (3a), (3c
) is designed to act with the I2C resonant circuit 12 on the frequency band f, and not to have any effect on the other frequency bands f,, f, and f4.

Furthermore, by determining the length of the filter elements (3b) and (3d) to be 5 and the length b, the filter elements have a capacitor CI (4) and a reactance (2).

(5) and 1. , (6) are determined to have desired values. Therefore, the filter elements (ab) and (3d) are designed to act as a 12C resonant circuit for the frequency band f4 and have no influence on the other frequency bands f I+ f and f4. Therefore.

The slit acts as a short-circuit surface 7 for the frequency bands f and f, and allows other frequency bands to pass through without any influence.This allows this waveguide filter to have a wide band. This makes it possible to operate as a band-stop filter with improved performance.

(2) In addition, in the above example, a wide band was achieved by providing filter elements (3a to 3d) of different lengths on the - side of the slit (2). The filter elements (3a to 3h) are further provided on each side of the filter elements (3a to 3d) and (3e to 3h).
The lengths of D Ill D 2a and D lb+ are respectively
By changing the distance between D and W and increasing the spacing between the filter elements, the resonance frequency band of the filter elements (3a to 3d) can be changed to f,
and the resonance frequency band of the filter element (3e to 3h) is f
, this waveguide filter can operate as a band rejection filter aiming at a wide band.

In addition, in the above embodiment, the filter element (3) provided in the slit (2) perpendicular to the tube axis direction in the rectangular waveguide (1)
Although four filter elements are used, any number of filter elements may be provided, and the same effect can be achieved even if the filter element (3) is oriented in either the left or right direction.

[Effects of the Invention] As described above, according to the present invention, by providing a plurality of filter elements with different resonance frequency bands in the slit part perpendicular to the tube axis in a rectangular waveguide, a wide-band resonant frequency characteristic can be achieved. There is an effect that a waveguide type filter having the following characteristics can be obtained.

[Brief explanation of the drawing]

1, 2, and 3 are a perspective view of a waveguide filter according to an embodiment of the present invention, an external view of a slot, and an equivalent circuit diagram of a filter element, and FIGS. 4 and 5 are a perspective view of a waveguide filter according to an embodiment of the present invention. A perspective view and an external view of the slot of a waveguide filter according to another embodiment, and FIGS. 6, 7, and 8 are a perspective view of a conventional waveguide filter, an external view of the slot, and an external view of the filter. FIG. 3 is an equivalent circuit diagram of the element. In the figure, (1) is a rectangular waveguide, (2) is a slit provided perpendicular to the tube axis of the rectangular waveguide, (3) is a filter element provided in the slit, and (4) is a waveguide. The capacitor C+, (S) between the waveguide filter and the slit has an actance L that corresponds to the path of the current flowing through the waveguide filter.
,, (6) is the reactance L21 that the slit exhibits without the waveguide filter. (7) is the resistance R between the slits. In addition, in FIG. 1, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) Consisting of a rectangular waveguide, a slit provided perpendicular to the tube axis within the rectangular waveguide, and a plurality of filter elements provided in the slit that resonate in series in a desired frequency band. A waveguide filter characterized in that a plurality of the filter elements are arranged in a row in a slit, and the length of each filter element is changed. (2) Consisting of a rectangular waveguide, a slit provided perpendicular to the tube axis within the rectangular waveguide, and a plurality of filter elements provided in the slit that resonate in series in a desired frequency band. A waveguide filter characterized in that a plurality of the filter elements are provided on two opposing sides of the slit, and the lengths of the filter elements provided on each side are changed.