JPH04267604A - dielectric coaxial resonator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric coaxial resonator used in dielectric filters for communication equipment, antenna duplexers, and the like.

0002

[Prior Art] Figure 5 shows a perspective view of a conventional dielectric coaxial resonator.
A cross-sectional view is shown in FIG. This dielectric coaxial resonator is provided with an electrode forming an inner conductor 15 on the inner peripheral surface of a through hole of a dielectric material 13 formed in a cylindrical shape, and an electrode forming an outer conductor 14 on the outer peripheral surface of the through hole. Connect one end of the opening to the short-circuited surface 1
6 electrodes were provided.

In general, the resonant frequency f0 of a dielectric coaxial resonator having the above structure is expressed by equation 1, where L is the length of the resonator and εr is the dielectric constant.

0004

[Formula 1]

A plurality of these dielectric coaxial resonators are used to create filters for communication equipment, such as bandpass filters (B
PF), band elimination filter (BEF)
When used as a resonant circuit constituting a dielectric coaxial resonator, etc., the resonant frequency of the dielectric coaxial resonator and the constants of circuit elements such as capacitors can be determined so as to obtain the required frequency characteristics of BPF (BEF). In order to manufacture a dielectric with a fixed resonant frequency, the relative permittivity εr of the dielectric material, the resonant frequency, and the length L of the resonator are determined from Equation 1.

[0006] In terms of manufacturing, the machining accuracy of the resonator length L (△
L), variation in relative permittivity εr of dielectric material (△εr)
In the mass production of filters using dielectric coaxial resonators, it is difficult to obtain stable frequency characteristics of the target filter (BPF, BEF, etc.) due to the variation in resonance frequency. It becomes difficult.

For this reason, for example, in the BPF, in the equivalent circuit shown in FIG. 4, the capacitors C2, C4, and C6 are made variable, so that the apparent resonance frequency of the dielectric resonator can be varied, that is, the resonance frequency is adjusted. Something with a mechanism was considered. A specific example is shown in FIG.

Coupling capacitors C1, C3, C5, and C7 shown in FIG. Capacitors C2, C4, C6 in Figure 4
is generated as a stray capacitance, and the BPF is adjusted by changing the resonance frequency by turning the adjustment screw 8.

[0009]

[Problems to be Solved by the Invention] In order to remove the resonant frequency adjustment mechanism that complicates the structure of the filter, instead of controlling the dielectric constant εr and the resonator length L of the dielectric coaxial resonator, A method is being used to manage the resonant frequency itself using a measuring device. In conventional dielectric resonator structures, the resonant frequency can be adjusted by increasing the resonant frequency by grinding the open end face of the dielectric resonator with a small processing tool, or by increasing the resonant frequency by grinding the open end face of the dielectric resonator with a small processing tool. There was a method to lower the resonance frequency by grinding. For example, several methods of increasing the resonance frequency have been proposed, as in Japanese Patent Laid-Open No. 127605/1983. However, these methods have the problem that a dielectric coaxial resonator whose resonance frequency is higher than the target cannot be used.

[0010] Furthermore, if it becomes necessary to lower the resonant frequency after incorporating a dielectric resonator having a conventional structure into a filter that does not have a resonant frequency adjustment mechanism, there is a problem that the filter cannot be adjusted. .

[0011] An object of the present invention is to provide a dielectric coaxial resonator structure that allows the resonant frequency to be easily lowered even after being incorporated into a filter without substantially degrading the Q of the dielectric resonator. It comes out.

0012

[Means for Solving the Problems] The present invention provides a cylindrical dielectric coaxial resonator having a through hole, in which an electrode forming an inner conductor is provided on the inner peripheral surface of the through hole, and In a dielectric coaxial resonator, an electrode forming an outer conductor is provided on the dielectric coaxial resonator, and an electrode forming a short circuit surface is provided on one end surface of the opening of the through hole in the dielectric material, and an electrode forming an outer conductor is provided on the opening end surface of the dielectric through hole. This is a dielectric coaxial resonator in which a plurality of protrusions are formed.

The present invention also provides a cylindrical dielectric coaxial resonator having a through hole, in which an electrode forming an inner conductor is provided on the inner peripheral surface of the through hole, and an outer conductor is provided on the outer peripheral surface. In the dielectric coaxial resonator, a dielectric coaxial resonator is provided with an electrode to form a short circuit, and an electrode to form a short circuit surface on one end surface of the opening of the through hole, wherein a plurality of protrusions are formed on an outer peripheral surface of the dielectric. It is a dielectric coaxial resonator.

[0014]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing one embodiment of the present invention.
Furthermore, a cross-sectional view is shown in FIG. In this embodiment, eight hemispherical protrusions 4 are provided on one end surface of the opening of the through hole of the cylindrical dielectric body 6, and are formed at eight concentric positions at the center of the outer and inner peripheries. outer conductor 2 on the inner surface, and inner conductor 3 on the inner peripheral surface.
Further, an electrode is formed on one end surface of the opening, including the protrusion 4, as the shorting surface 1. In order to lower the resonant frequency of this dielectric coaxial resonator, the protrusion 4
All you have to do is remove it with a processing tool. The range in which the resonance frequency is lowered can be changed depending on the number and position of the protrusions to be removed. Frequency adjustment can be similarly performed when a protrusion is provided on the outer peripheral surface. Note that the shape, number, and position of these protrusions can be freely set.

[0016] The above description has been made regarding a cylindrical dielectric coaxial resonator, but it can also be applied to a prismatic dielectric coaxial resonator or an integrally molded dielectric resonator in which two or more elements are integrated.

[0017]

Effects of the Invention The dielectric coaxial resonator of the present invention has improved manufacturing accuracy (△L) and variation in dielectric permittivity (△εr).
), even if the resonant frequency becomes higher than the target value, the resonant frequency can be lowered without significantly deteriorating the Q by scraping off the protrusion on the short-circuit surface.

Furthermore, even after being assembled in a case as a filter, the resonant frequency can be lowered without replacing the dielectric, and the yield of the product can be improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the present invention.

FIG. 2 is a sectional view showing one embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram of an example of a bandpass filter.

FIG. 4 is a configuration example of a bandpass filter.

FIG. 5 is a perspective view of a conventional dielectric coaxial resonator.

FIG. 6 is a cross-sectional view of a conventional dielectric coaxial resonator.

[Explanation of symbols]

1, 16 Short circuit electrode 2, 14 Outer conductor 3, 15 Inner conductor 4 Protrusion 5 Open end surface 6, 13 Dielectric 7 Case 8 Adjustment screw 9 Input/output section 10 Metal fittings 11 Printed circuit board 12 Dielectric resonator

Claims (2)

[Claims] 1. A cylindrical dielectric coaxial resonator having a through hole, wherein an electrode forming an inner conductor is provided on the inner peripheral surface of the through hole, and an electrode forming an outer conductor is provided on the outer peripheral surface of the through hole. In the dielectric coaxial resonator, the dielectric coaxial resonator is provided with an electrode that forms a short circuit surface on one end surface of the opening of the through hole, and a plurality of protrusions are formed on one end surface of the opening of the dielectric through hole. A dielectric coaxial resonator characterized by: 2. A cylindrical dielectric coaxial resonator having a through hole, wherein an electrode forming an inner conductor is provided on the inner peripheral surface of the through hole, and an electrode forming an outer conductor is provided on the outer peripheral surface of the through hole. The dielectric coaxial resonator is provided with an electrode that forms a short circuit surface on one end surface of the opening of the through hole, wherein a plurality of protrusions are formed on the outer peripheral surface of the dielectric. dielectric coaxial resonator.