JP2004147001A - Band pass filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a band pass filter in which an operation for adjusting a transmitted frequency is easy and in which an adjusting range of the frequency and the coupling is not narrowly limited. <P>SOLUTION: The band pass filter is provided with a rectangular waveguide 11 and 15, each of which has a rectangular waveguide inside and in which a plurality of partition walls 12 that are disposed on an inner wall side facing to one inner wall from one inner wall and that form asymmetrical inductive windows are integrally formed, a dielectric 14 arranged on the inner wall facing to one wall and frequency/coupling degree adjusting screws 13 which are arranged in positions away from the dielectric 14 and the partition walls 12 and adjust the transmitted frequency and the coupling of the waveguide by length projected to the inductive window. The dielectric 14 may be formed of fluororesin. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bandpass filter, and more particularly, to a bandpass filter configured by combining a rectangular waveguide and a dielectric.
[0002]
[Prior art]
Conventionally, a bandpass filter has been proposed in which an inductive window is formed by partitioning a rectangular waveguide from a bottom surface of the rectangular waveguide at an appropriate length to operate as a filter (for example, see Patent Document 1).
[0003]
As shown in FIG. 6, in this band-pass filter, a plurality of partition walls 32 forming an asymmetric inductive window 40 are integrally formed at predetermined intervals in a rectangular waveguide 39 having an opening on one side in accordance with a band frequency. And a cover 35 joined so as to close the opening surface of the rectangular waveguide 39, and a frequency adjusting screw 37 for adjusting the propagation frequency of the rectangular waveguide 39 is provided at an intermediate position between the partition walls 32. And a coupling degree adjusting screw 38 for adjusting the coupling degree is provided from the cover 35 toward the partition wall 32 to adjust the coupling degree.
[0004]
[Patent Document 1]
Japanese Patent No. 3025930
[Problems to be solved by the invention]
However, in the above-described conventional band-pass filter, it is necessary to increase the insertion amount of the frequency adjustment screw 37 in order to lower the propagation frequency. However, if the insertion amount of the frequency adjustment screw 37 is increased, the pass band width is reduced. Each time, the pass bandwidth must be adjusted with the coupling degree adjusting screw 38, and the operation is complicated. In addition, there is a problem that the adjustment by the adjustment screws 37 and 38 has a limit, and the adjustment range of the frequency and the degree of coupling is narrowly limited.
[0006]
In view of the above, the present invention has been made in view of the above-described problems in the conventional band-pass filter. In adjusting the propagation frequency, the operation is easy, and the adjustment range of the frequency and the coupling degree may be narrowly limited. Aim to provide no bandpass filter.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is a band-pass filter, having a rectangular waveguide inside, and extending from one inner wall to an inner wall facing the one inner wall. A rectangular waveguide integrally formed with a plurality of partition walls forming an asymmetric inductive window, a dielectric disposed on an inner wall opposed to the one inner wall, and separated from the dielectric and the partition wall And a frequency / coupling adjusting screw for adjusting the propagation frequency and the coupling of the waveguide by a length protruding from the inductive window.
[0008]
According to the first aspect of the present invention, the electric field is concentrated on the dielectric by installing the dielectric so as to face the partition wall forming the asymmetric inductive window, and the frequency / coupling degree adjusting screw is formed. By inserting the adjustment screw, the influence of the adjustment screw on the electromagnetic field in the waveguide is stronger than in air, and the adjustment can be performed with a small insertion amount. Also, by appropriately selecting the thickness and permittivity of the dielectric, a desired pass bandwidth can be realized in a wide frequency range. Further, the resonance frequency and the coupling degree can be simultaneously adjusted by the frequency / coupling degree adjusting screw.
[0009]
According to a second aspect of the present invention, as a preferred embodiment of the band-pass filter according to the first aspect, the dielectric is formed of a fluororesin.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0011]
FIGS. 1 to 3 show an embodiment of a band-pass filter according to the present invention. This band-pass filter has a U-shaped waveguide having an opening on one side formed in a main body 11 made of a conductive material. A plurality of partition walls 12 for separating the waveguide from the inner wall are integrally formed. The cover 15 made of a conductive material is provided so as to cover the opening side surface of the waveguide with respect to the main body 11, thereby forming an asymmetric inductive window in the waveguide.
[0012]
A positioning groove 16 is formed in the opening of the main body 11, and the dielectric 14 is fixed in the positioning groove 16. Further, a plurality of frequency / coupling adjusting screws 13 for adjusting the propagation frequency and the coupling of the waveguide by the length protruding into the main body 11 are arranged at positions separated from the dielectric 14 and the partition wall 12.
[0013]
In the bandpass filter having the above configuration, since the dielectric 14 is inserted into the rectangular waveguide, the guide wavelength is shortened, the coupling degree is increased, and the pass band width is increased. This function becomes more conspicuous as the thickness of the dielectric 14 is increased and as the dielectric constant is increased. In addition, when the frequency / coupling degree adjusting screw 13 near the dielectric 14 is inserted, since the electromagnetic field is concentrated by the dielectric 14, it is applied to the electromagnetic field in the waveguide as compared with the air. The effect is increased, and the effect can be obtained with a small amount of screw inserted.
[0014]
Next, as one embodiment of the band-pass filter according to the present invention, FIG. 4 shows a frequency shift actual measurement diagram in a band-pass filter in which the pass bandwidth of a 23 GHz band is designed to be 800 MHz.
[0015]
It can be seen that when a fluororesin having a thickness of 1.0 mm is used as the dielectric, the propagation frequency is lower by about 150 MHz and the pass bandwidth is higher by about 100 MHz than when no fluororesin is used. At this time, the insertion amount of the frequency / coupling degree adjusting screw 13 is the same with or without the fluororesin. In other words, when the dielectric 14 is not provided, it is necessary to further insert the frequency / coupling degree adjusting screw 13 in order to obtain a pass band width. Bandwidth can be obtained.
[0016]
Next, another embodiment of the band-pass filter according to the present invention will be described with reference to FIG.
[0017]
This band-pass filter shows a case where the main body is manufactured by casting, and since a slight taper angle is generated in the main body 21 in which the partition wall 22 is integrated, it can be fixed only by placing the dielectric 24 in the opening. By covering the opening of the main body 21 with the cover 25, a band-pass filter can be formed, and the same characteristics as in the above embodiment can be obtained.
[0018]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a band-pass filter that is easy to operate in adjusting the propagation frequency and that does not restrict the adjustment range of the frequency and the coupling degree narrowly.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing an embodiment of a bandpass filter according to the present invention.
FIG. 2 is a side view of the bandpass filter of FIG.
FIG. 3 is a sectional view taken along line AA of FIG. 1;
FIG. 4 is an actual measurement graph showing a relation between a propagation frequency of a band-pass filter similar to the band-pass filter of FIG. 1 and a -3 dB pass bandwidth.
FIG. 5 is a cross-sectional view showing another embodiment of the bandpass filter according to the present invention.
FIG. 6 is an exploded perspective view showing an example of a conventional band-pass filter.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Main body 12 Partition wall 13 Frequency / coupling degree adjusting screw 14 Dielectric 15 Cover 16 Positioning groove 18 Coupling degree adjusting screw 19 Waveguide 21 Main body 22 Partition wall 23 Frequency / coupling degree adjusting screw 24 Dielectric 25 Cover

Claims (2)

A rectangular waveguide having a rectangular waveguide inside, and integrally formed with a plurality of partition walls extending from one inner wall to an inner wall facing the one inner wall to form an asymmetric inductive window When,
A dielectric disposed on an inner wall opposite to the one inner wall,
A frequency / coupling degree adjusting screw arranged at a position separated from the dielectric and the partition wall and adjusting a propagation frequency and a coupling degree of the waveguide by a length protruding from the inductive window, Band pass filter. 2. The band-pass filter according to claim 1, wherein said dielectric is formed of a fluororesin.

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