JPH07106806A - Cavity resonator - Google Patents

Abstract

PURPOSE:To obtain the cavity resonator in which the degree of coupling between the cavity resonator and square waveguide and the resonance frequency can be designed independently by preventing simultaneous excitation of the TM0ij mode being a degenerate mode of the cavity resonator. CONSTITUTION:The cavity resonator 2 and a square waveguide 4 are coupled by two coupling holes 6A provided to a bottom of the cavity resonator 2 and two coupling holes 6B provided to an H side of a square waveguide 4. The coupling holes 6A provided to the bottom side of the cavity resonator 2 are located at positions on a diameter and apart by nearly 1/2 wavelength with respect to a cut-off frequency of the cavity resonator 2 having a center point inbetween. The coupling holes 6B provided to the H side of the square waveguide 4 are located to positions in parallel with the guide axis and corresponding to the coupling holes 6A provided to the bottom side of the cavity resonator 2 not on the guide axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cavity resonator used for a waveguide oscillator of microwaves, millimeter waves, etc., in which a coupling hole is provided to remove unnecessary modes generated. And the rectangular waveguide.

[0002]

2. Description of the Related Art TE0ij mode cylindrical cavity resonator (hereinafter referred to as
It is a cavity resonator. ), Various inventions have been made as a method for removing an unnecessary mode that occurs when using (). As an invention of such a cavity resonator, Japanese Patent Publication No. 55-21487
The band stop filter for extremely short waves described in the publication of the publication can be mentioned.

FIG. 6 shows the structure of this band-stop filter for extremely short waves. In this structure, 2 is a cavity resonator, 4 is a rectangular waveguide, 30 is a coupling hole, 12 is a bottom portion of the cavity resonator 2,
Reference numeral 8 is an H-plane wall of the rectangular waveguide, and 10 is an E-plane wall of the rectangular waveguide.

FIG. 7 is a plan view showing the coupling portion in the conventional example shown in FIG. 6, and shows the positional relationship between the cavity resonator 2, the rectangular waveguide 4 and the coupling hole 30. The method of coupling the cavity resonator 2 and the rectangular waveguide 4 is as follows.
Is coupled to the H-face wall 8 provided with the coupling hole 30. The coupling at this time is based on the bottom part 1 of the cavity resonator 2.
The radial magnetic field at 2 and the lateral magnetic field at the H-plane wall 8 of the rectangular waveguide 4 are generated via the coupling hole 30.

Since the cylindrical cavity resonator is a multimode cavity, there are essentially many spurious modes, but the spurious modes can be prevented by using this extremely short-wave band stop filter.

[0006]

However, the above-mentioned conventional ultra-short band stop filter cannot prevent the TM1ij mode which is a degenerate mode that is simultaneously excited with the cavity resonator.

FIG. 8 is a diagram showing the relationship between the size of the coupling hole of the cavity resonator, the degree of coupling between the cavity resonator and the rectangular waveguide, and the resonance frequency. When designing the coupling degree and the resonance frequency, the size of the coupling hole is usually changed in order to adjust the coupling degree, but as can be seen from FIG. 8, adjusting the coupling degree also changes the resonance frequency. Therefore, the coupling degree and the resonance frequency could not be designed independently.

In view of the above problems, the present invention prevents a TM0ij mode, which is a degenerate mode, from being excited at the same time, and allows the cavity resonator and the rectangular waveguide to be independently designed in terms of the degree of coupling and the resonance frequency. It is intended to provide a resonator.

[0009]

In order to achieve the above object, a cavity resonator according to the present invention has two coupling holes provided in the bottom surface of the cavity resonator and an H-plane of a rectangular waveguide. Provided in 2
The cavity resonator and the rectangular waveguide are coupled by the individual coupling holes, and the coupling hole provided at the bottom of the cavity resonator is on the diameter and the cutoff frequency of the cavity resonator is almost The coupling hole provided on the H surface of the rectangular waveguide at a position separated by ½ wavelength is parallel to the tube axis and corresponds to the coupling hole provided on the bottom surface of the cavity resonator. It is not located on the tube axis.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. It should be noted that the same components as those of FIG. 6 showing the conventional technique are designated by the same reference numerals, and the duplicate description thereof will be omitted.

FIG. 1 is a diagram showing a coupled state of a cavity resonator and a rectangular waveguide. In FIG. 1, 6A and 6B are coupling holes. Here, A and B indicate the cavity resonator side and the rectangular waveguide side, respectively. FIG. 2 is a plan view showing a coupling portion between the cavity resonator 2 and the rectangular waveguide 4 shown in FIG.

1 and 2, the coupling hole 6A provided in the bottom surface portion 12 of the cavity resonator 2 is on the diameter of the bottom surface portion 12 and the center point of the bottom surface portion 12 is sandwiched between the cavity holes 2 of the cavity resonator 2. It is located at a distance of about 1/2 wavelength of the cutoff frequency. Rectangular waveguide 4
The coupling hole 6B provided in the H-face wall 8 is parallel to the tube axis and is provided in the bottom surface portion 12 of the cavity resonator 2.
It is a position corresponding to A and not at a position on the tube axis.

FIG. 3 is a diagram showing a magnetic field when the cavity resonator 2 is viewed from the bottom surface portion 12. Cavity resonator 2
In the coupling hole 6A and the coupling hole 6B, the radial magnetic field at the bottom surface portion 12 of the cavity resonator 2 and the lateral magnetic field at the E-plane wall 10 of the rectangular waveguide 4 are in the same direction in the coupling hole 6A and the coupling hole 6B. It is done from that.

FIGS. 4 (a) and 4 (b) are views showing the state of the magnetic field in the TE01 mode and the TM11 mode which is the degenerate mode and the position of the coupling hole as an example of the cavity resonator.

In the TM11 mode shown in FIG. 4A, the traveling directions of the magnetic field at the positions of the two coupling holes are the same,
The phase difference of the magnetic field is zero. Therefore, since the distance between the two coupling holes is 1/2 wavelength of the cutoff frequency of the cavity resonator, the two coupling holes interfere with the magnetic field in the rectangular waveguide, and simultaneous excitation of TM11 can be prevented.

In the TE01 mode shown in FIG. 4 (b),
The magnetic fields at the positions of the two coupling holes have different traveling directions, and the phase difference of the magnetic fields is 1/2 of the cutoff frequency of the cavity resonator.
Wavelength. Therefore, the distance between the two coupling holes is set to ½ wavelength of the cutoff frequency of the cavity resonator to couple with the magnetic field in the rectangular waveguide.

Therefore, in the cavity resonator of the present invention, only the TE0ij mode is excited and the TM0ij mode, which is the degenerate mode, is prevented from being simultaneously excited, so that the unloaded Q of the cavity resonator can be increased.

Next, FIG. 5 shows the relationship between the distance of the coupling hole from the tube axis 14, the degree of coupling between the cavity resonator and the rectangular waveguide, and the resonance frequency of the cavity resonator.

As can be seen from this figure, when the position of the coupling hole 6B from the tube axis 14 is changed, the resonance frequency is constant and the degree of coupling increases. Therefore, when the coupling hole 6B is provided at the position of the E-plane wall 10, since the distance from the tube axis 14 is constant, the coupling degree cannot be changed by changing the position of the coupling hole 6B.

In the present invention, focusing on this point, the coupling hole 6B is made H
By providing the surface wall 8, the resonance frequency can be kept constant and the coupling degree can be changed.

[0021]

As described above, according to the present invention,
TM0ij is a degenerate mode of a cavity resonator by providing a coupling hole on the H surface of a rectangular waveguide so as to be parallel to the tube axis.
It is possible to prevent the modes from being excited at the same time and increase the no-load Q of the cavity resonator.

Further, the coupling degree between the cavity resonator and the rectangular waveguide and the resonance frequency of the cavity resonator can be designed independently.

[Brief description of drawings]

FIG. 1 is a diagram showing a coupled state of a cavity resonator of the present invention and a rectangular waveguide.

FIG. 2 is a plan view showing a coupling portion between the cavity resonator of FIG. 1 and a rectangular waveguide.

FIG. 3 is a diagram showing a state of a magnetic field when the cavity resonator is viewed from the bottom surface portion.

FIG. 4A is a diagram showing a state of a magnetic field of a TM11 mode cavity resonator and a position of a coupling hole. (B) is a diagram showing a magnetic field and a position of a coupling hole of the TE01 mode cavity resonator.

FIG. 5 shows the relationship between the distance of the coupling hole from the tube axis, the degree of coupling between the cavity resonator and the rectangular waveguide, and the resonance frequency of the cavity resonator.

FIG. 6 shows the configuration of a conventional band-stop filter for extremely short waves.

7 is a plan view showing a coupling portion between the cavity resonator of FIG. 6 and a rectangular waveguide.

FIG. 8 is a diagram showing the relationship between the size of a coupling hole of a conventional cavity resonator, the cavity resonator, the degree of rectangular waveguide coupling, and the resonance frequency.

[Explanation of symbols]

 2 Cavity Resonator 4 Rectangular Waveguide 6A Coupling Hole 6B Coupling Hole 8 H-Side Wall 10 E-Side Wall 12 Bottom Part 14 Tube Axis 30 Coupling Hole

Claims (1)

[Claims] 1. A TE0ij (i, j is a natural number) mode cylindrical cavity resonator and a rectangular waveguide, wherein two coupling holes provided in the bottom surface of the cavity resonator and the rectangular waveguide are used. The cavity resonator and the rectangular waveguide are coupled by two coupling holes provided on the H surface, and the coupling hole provided on the bottom surface of the cavity resonator is diametrical and sandwiches the center point. The coupling hole provided on the H-plane of the rectangular waveguide is located at a position separated by about 1/2 wavelength of the cutoff frequency of the cavity resonator, and the coupling hole is parallel to the tube axis and provided on the bottom surface of the cavity resonator. A cavity resonator characterized in that it is located at a position corresponding to the coupling hole and not on the tube axis.