JP2006237824A - Variable filter, and resonator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable filter that is downsized as compared with prior arts and can easily carry out frequency adjustment. <P>SOLUTION: The variable filter includes: a conductive metallic cavity 2; a dielectric resonator 3 installed in the metallic cavity 2; and a frequency adjustment mechanism 5 with a disk board 7 having an opposite face formed to face the dielectric resonator 3. The dielectric resonator 3 is configured such that electromagnetic fields are orthogonal to each other on the xy plane and the electromagnetic field distribution on the xz plane in a direction of the z axis is the same as the electromagnetic field distribution on the yz plane in the direction of the z axis. The disk board 7 of the frequency adjustment mechanism 5 is arranged in parallel with the xy plane and configured to be movable in the direction of the z axis and changing the distance between the disk board 7 and the xy plane of the dielectric resonator 3 provides the same amount of perturbation to the two electromagnetic fields orthogonal to each other on the xy plane. Thus, the adjustment amount of the resonance frequency is almost the same in two modes. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a filter used in a radio communication device using a high frequency band such as a microwave band and a millimeter wave band, and more particularly to a variable filter having a variable frequency band for filtering and a resonator used in the variable filter. About.

  In the wireless communication device, a filter is used to select a desired frequency band. As a filter for a wireless communication device, a variable filter in which a frequency band to be filtered is variable when performing communication in a wide frequency band may be used. The variable filter has a function of changing the tuning frequency while maintaining the filter characteristics within a specific frequency band.

  The variable filter is provided with a frequency adjustment mechanism. The frequency adjusting mechanism changes and sets the resonance frequency of each element of the variable filter to a desired frequency simultaneously and in the same amount. The frequency adjusting mechanism calculates a deviation from a desired frequency based on a detected radio wave from each element of the variable filter, and mechanically adjusts the frequency. When a multistage variable filter is configured using a plurality of resonators, a frequency adjustment mechanism is provided for each resonator.

  There are many types of resonators used in variable filters. In general, a so-called single mode resonator that uses one resonance by one resonator is used. When a multistage filter is configured using a single mode resonator, the resonator and the frequency adjustment mechanism are required by the number of stages, and the entire filter tends to be large.

  On the other hand, a multistage variable filter may be configured by a so-called dual mode resonator that uses two resonances by one resonator. When a dual mode resonator is used, even when a multi-stage filter is configured, the number of resonators that is half the number of filter stages may be used, and thus the size of the filter can be reduced.

  A typical example of a dual mode resonator is a dielectric resonator using an EH11δ mode. As a frequency adjustment mechanism of the EH11δ mode dielectric resonator, metal screws are usually used. FIG. 3 shows an electric dipole of the EH11δ mode in the dielectric resonator. FIG. 3 shows an electric dipole with the bottom surface of the cylindrical dielectric resonator 3 as the xy plane. The electric dipole E1 is directed in the y-axis direction and the electric dipole E2 is directed in the x-axis direction, and the electric dipole E1 and the electric dipole E2 are orthogonal to each other in the xy plane.

A conventional frequency adjustment mechanism will be described with reference to FIG.
In FIG. 6, two frequency adjustment screws (frequency adjustment mechanisms) 9 and 10 are provided to face the side surface of the cylindrical dielectric resonator 8. If the normal direction of the bottom surface of the dielectric resonator 8 is the z-axis, a frequency adjustment screw 9 is provided in the x-axis direction that forms an orthogonal coordinate system with the z-axis, and a frequency adjustment screw 10 is provided in the y-axis direction. The frequency adjusting screws 9 and 10 are metal screws. By moving the frequency adjusting screw 9 in the x-axis direction, the distance between the frequency adjusting screw 9 and the dielectric resonator 8 varies, and the electric dipole E2 changes. By moving the frequency adjusting screw 10 in the y-axis direction, the distance between the frequency adjusting screw 10 and the dielectric resonator 8 varies and the electric dipole E1 changes. By bringing the frequency adjusting screws 9 and 10 closer to the side surface of the dielectric resonator 8, the resonance frequency can be lowered by perturbation of the electric field.

  Since the electric dipole E1 and the electric dipole E2 are orthogonal to each other in the xy plane, they can be controlled independently for each mode. However, when a variable filter is configured using a dual mode resonator having a structure as shown in FIG. 6, two frequency adjustment mechanisms are required for one cavity, so that the control becomes complicated, and the variable filter The overall configuration is increased and the advantage of using a dual mode resonator is impaired.

  In view of the above problems, an object of the present invention is to provide a variable filter that is smaller than the conventional one and that can easily adjust the frequency, and a resonator used in the variable filter.

  The variable filter of the present invention that solves the above-described problems includes a conductive cavity, a resonator installed in the cavity, and a facing surface provided to face a predetermined first surface of the resonator. A frequency adjusting mechanism. In the variable filter, the resonator has the predetermined first surface in two planes in which two or more electromagnetic fields are orthogonal to each other and orthogonal to the predetermined first surface and orthogonal to each other. The electromagnetic field distribution in the normal direction of one surface is configured to be the same, and the opposing surface of the frequency adjusting mechanism is arranged to be parallel to the predetermined first surface, and the predetermined surface The first surface of the resonator is movable in the normal direction, and the distance between the facing surface of the frequency adjusting mechanism and the predetermined first surface of the resonator changes, whereby the predetermined first The two or more electromagnetic fields orthogonal to each other are configured to give the same amount of perturbation.

In order to give the same amount of perturbation to two electromagnetic fields orthogonal to each other on the predetermined first surface, the adjustment amount of the resonance frequency can be made substantially the same in the two modes. Therefore, it is possible to make one frequency adjustment mechanism that has conventionally been prepared for two electromagnetic fields.
If the predetermined first surface is the xy plane of the Cartesian coordinate system, the two surfaces orthogonal to the predetermined first surface and orthogonal to each other are the xz plane and the yz plane, and the normal direction of the predetermined first surface is It becomes the z-axis direction. The predetermined first surface is formed on the surface of the resonator, but the two surfaces orthogonal to the predetermined first surface and orthogonal to each other are not necessarily on the surface of the resonator. For example, if the resonator is a rectangular parallelepiped, these three surfaces are on the surface of the resonator. In this case, for example, a cylindrical bottom surface is a predetermined first surface, and the other two surfaces are surfaces that are not on the surface of the resonator.

  In such a variable filter, for example, the facing surface of the frequency adjusting mechanism is formed in the same shape and size as the predetermined first surface. By forming in this way, frequency adjustment is performed more effectively.

  The frequency adjusting mechanism includes, for example, a plate portion on which the facing surface is formed, and an adjustment portion that moves the plate portion in the normal direction of the predetermined first surface. The plate portion moves by moving the adjustment portion in the normal direction of the predetermined first surface, and the distance between the facing surface and the predetermined first surface varies.

  The resonator is, for example, a dual-mode dielectric resonator, and a bottom surface is formed in a columnar shape corresponding to the predetermined first surface. In this case, in the frequency adjusting mechanism, the facing surface is formed in the same shape and size as the bottom surface. Specifically, the resonator is a dielectric resonator using an EH11δ mode, for example.

  In the resonator according to the present invention, the two or more electromagnetic fields are orthogonal to each other on the predetermined first surface, and the method of the predetermined first surface in two surfaces orthogonal to the predetermined first surface and orthogonal to each other. A resonator formed so that the electromagnetic field distribution in the linear direction is the same, and is disposed in parallel with the predetermined first surface and is movable in the normal direction of the predetermined first surface The two or more electromagnetic fields orthogonal to each other at the predetermined first surface by changing a distance between the facing surface of the frequency adjusting mechanism and the predetermined first surface. Are given the same amount of perturbation.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram for explaining the configuration of the variable filter 1 of the present embodiment. FIG. 2 is a diagram for explaining the configuration of the resonator according to the present embodiment.

  The variable filter 1 is configured by providing a cylindrical dielectric resonator 3 in a metal cavity 2. The dielectric resonator 3 is placed in contact with the bottom surface of a support 4 provided in the metal cavity 2, and is disposed in a hollow space in the metal cavity 2. The dielectric resonator 3 has a cylindrical shape in this embodiment, but is not limited to this, and may have another shape such as a rectangular parallelepiped. The metal cavity 2 may be a cavity made of a conductor instead of a metal. The dielectric resonator 3 is, for example, a double mode resonator. The support 4 is preferably made of a material having a low dielectric constant and a low dielectric loss tangent. 1 and 2, the normal direction of the bottom surface of the dielectric resonator 3 is taken as the z-axis, and the bottom surface is taken as the xy plane.

  A frequency adjusting mechanism 5 is provided opposite to the bottom surface of the dielectric resonator 3 that is in contact with the support table 4. The frequency adjusting mechanism 5 is for adjusting the resonance frequency of the dual mode by the dielectric resonator 3. The frequency adjustment mechanism 5 includes an adjustment screw portion 6 and a disc portion 7, and the disc portion 7 faces the bottom surface of the dielectric resonator 3. The adjustment screw portion 6 has a cylindrical shape, and one end is fixed to the surface of the disc portion 7 opposite to the surface (facing surface) facing the dielectric resonator 3. The disc portion 7 is formed of a conductor such as a metal, but the adjustment screw portion 6 is not necessarily a conductor.

  For example, the opposing surface of the disc portion 7 facing the dielectric resonator 3 is formed in the same shape and size as the bottom surface of the dielectric resonator 3, so that the frequency adjustment can be effectively performed. The adjustment screw portion 6 is a movable mechanism formed so as to be movable in the z-axis direction. For example, the adjustment screw portion 6 is threaded and the adjustment screw portion 6 is rotated to be movable in the z-axis direction. Further, it may be movable in the z-axis direction by pushing in or pulling out in the z-axis direction. As the adjusting screw portion 6 moves in the z-axis direction, the disc portion 7 moves in the z-axis direction. When the disc portion 7 moves in the z-axis direction, the disc portion 7 approaches or separates from the bottom surface of the dielectric resonator 3 and the distance between the disc portion 7 and the dielectric resonator 3 changes. It is supposed to be. The resonance frequency of the dielectric resonator 3 can be changed by changing the distance between the disc portion 7 and the dielectric resonator 3.

  3, 4 and 5 are diagrams showing the distribution of the electric dipoles E1 and E2 by the dielectric resonator 3 in the EH11δ mode. As can be seen from these figures, the electric dipoles E1 and E2 of the dual modes are orthogonal to each other in the xy plane, and the distribution in the z-axis direction is the same in the xz plane and the yz plane.

  Therefore, by changing the distance between the disk portion 7 of the frequency adjusting mechanism 5 and the bottom surface of the dielectric resonator 3, the same amount of perturbation can be given to the electric fields of the orthogonal modes. The frequency adjustment amount can be made substantially the same in the two modes.

  The closer the disc portion 7 of the frequency adjusting mechanism 5 is to the dielectric resonator 3, the greater the amount of perturbation of the electric field and the lower the resonant frequency. Conversely, when the disc portion 7 is moved away from the dielectric resonator 3, the resonance frequency increases. In such a configuration, since only one frequency adjustment mechanism 5 is required, frequency adjustment is facilitated, and the variable filter 1 can be reduced in size.

  In this embodiment, the resonator is described using a dielectric material, but the present invention is not limited to this, and a conductive material may be used. Also, the dual mode need not be EH11δ. Any resonator in which two or more electromagnetic fields are orthogonal to each other on the xy plane and have the same electromagnetic field distribution in the z-axis direction on the xz plane and the yz plane can be used in the present invention.

The figure for demonstrating the structure of the variable filter of this embodiment. The figure for demonstrating the structure of the resonator of this embodiment. The figure showing distribution of the electric dipole by a dielectric resonator. The figure showing distribution of the electric dipole by a dielectric resonator. The figure showing distribution of the electric dipole by a dielectric resonator. The figure for demonstrating the structure of the conventional dielectric resonator and the frequency adjustment mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Variable filter 2 Metal cavity 3, 8 Dielectric resonator 4 Support stand 5 Frequency adjustment mechanism 6 Adjustment screw part 7 Disk part 9, 10 Frequency adjustment screw

Claims (6)

A conductive cavity;
A resonator installed in the cavity;
A frequency adjustment mechanism having an opposing surface provided to oppose a predetermined first surface of the resonator,
In the resonator, two or more electromagnetic fields are orthogonal to each other on the predetermined first surface, and the normal line of the predetermined first surface in two surfaces orthogonal to the predetermined first surface and orthogonal to each other. The electromagnetic field distribution in the direction is the same,
The opposed surface of the frequency adjusting mechanism is arranged to be parallel to the predetermined first surface, and is configured to be movable in a normal direction of the predetermined first surface,
The same amount of perturbation with respect to the two or more electromagnetic fields orthogonal to each other on the predetermined first surface by changing the distance between the facing surface of the frequency adjusting mechanism and the predetermined first surface of the resonator Is configured to give
Variable filter. The facing surface of the frequency adjusting mechanism is formed in the same shape and size as the predetermined first surface.
The variable filter according to claim 1. The frequency adjustment mechanism is
A plate portion on which the facing surface is formed;
An adjustment part that moves the plate part in the normal direction of the predetermined first surface,
The variable filter according to claim 1 or 2. The resonator is a dual-mode dielectric resonator, and a bottom surface is formed in a columnar shape corresponding to the predetermined first surface,
In the frequency adjusting mechanism, the facing surface is formed in the same shape and size as the bottom surface.
The variable filter according to claim 1. The resonator is a dielectric resonator using an EH11δ mode.
The variable filter according to claim 4. Two or more electromagnetic fields are orthogonal on the predetermined first surface, and the electromagnetic field distribution in the normal direction of the predetermined first surface in two surfaces orthogonal to the predetermined first surface and orthogonal to each other is A resonator formed to be the same,
A frequency adjusting mechanism having a facing surface arranged in parallel to the predetermined first surface and movable in a normal direction of the predetermined first surface;
The same amount of perturbation is applied to the two or more electromagnetic fields orthogonal to each other in the predetermined first surface by changing the distance between the facing surface of the frequency adjusting mechanism and the predetermined first surface. It is configured,
Resonator.

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