JPS61237501A - Dielectric coaxial resonator - Google Patents

Abstract

PURPOSE:To improve the spurious response characteristic by providing a ground electrode corresponding to an electrode formed individually coupling electrostatically dielectric coaxial resonators. CONSTITUTION:Individual electrode patterns 101-103 coupling electrostatically dielectric coaxial resonators 21-23 together are formed to one major plane of a dielectric substrate 9, and an inner conductor 11 of the dielectric coaxial resonators 21-23 is connected thereto. A common grounding electrode pattern 12 opposing to the coupling electrode patterns 101-103 is formed to other major plane of the dielectric substrate 9. Thus, electrostatic capacitances formed by the coupling patterns 101-103 and the grounding electrode pattern 12 are formed in parallel with the dielectric coaxial resonators 21-23 respectively, the frequency of each resonator state is adjusted by the parallel capacitance and the spurious response characteristic is improved by adjusting the electrode patterns.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a dielectric coaxial resonator used, for example, as a filter device.

(Prior Art) In general, this type of dielectric coaxial resonator has a through hole formed in a dielectric material such as ceramic, and a center conductor and an outer conductor formed in the through hole and the outer peripheral surface of the lightning dielectric material. , a resonant element having an electrode formed on one end surface that short-circuits a center conductor and an outer conductor is placed in a conductive shielding case, and at least a part of the outer conductor of the resonant element is electrically conductive to the case. It is known that the device is stored in a connected state.

However, when using such a configuration as a band-pass filter, if the resonant element is a 174-wavelength resonant type, the fundamental resonance frequency is It was necessary to provide a trap element that resonates at a frequency three or five times the frequency. The trap element is constructed by, for example, connecting the center conductor of a dielectric coaxial resonator and an input/output terminal via a capacitor, and the outer conductor is grounded. This is done so that series resonance occurs at the desired frequency. Therefore, there are disadvantages in that the number of parts is large and the external dimensions of the filter are large. Incorporating a low pass filter rather than a trap element greatly exacerbates these drawbacks.

(Objective of the Invention) The object of the present invention is to reduce the apparent resonance frequency of the fundamental wave without changing the harmonic resonance frequency itself without increasing the number of parts or increasing the external dimensions of the filter. This is to improve the filter characteristics by driving the spurious response to a position deviated from a frequency value that is twice the fundamental resonance frequency.

(Structure of the Invention) In order to achieve such an object, the present invention includes a plurality of resonant elements arranged in parallel, and a dielectric substrate arranged on the open end surface side of each resonant element. An electrode for electrostatically coupling these resonant elements to each other is individually formed on one main surface of the substrate, and an electrode for electrostatic coupling between the resonant elements is formed on the other main surface of the dielectric substrate. A frequency adjustment electrode was formed to lower the fundamental resonant frequency without changing the harmonic resonant frequency.

(Effects of the Invention) According to such a configuration, the conventional trap element and low-pass filter are not required, so the number of parts is reduced, the structure is simplified, and a small and inexpensive filter can be provided.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 is a partially cutaway perspective view of the dielectric coaxial resonator of this embodiment, and FIG. 2 is an equivalent circuit diagram thereof. In these figures, reference numeral 1 denotes a shielding case, and this case 1 is made of a conductive material such as an aluminum alloy. In this case 1, a plurality of resonant elements 2+, 22, 23, which serve as filter elements, are arranged and housed in parallel adjacent to each other. Each resonant element 21...
- is a cylindrical ceramic dielectric body 4 with a through hole 3 in the center
A center conductor 5 made of an electrode film such as copper is formed on the inner peripheral surface of the dielectric, that is, the peripheral surface of the through hole 3, and an outer conductor 6 is similarly formed on the outer peripheral surface.

An electrode film is formed entirely on one end surface 1 of this dielectric, and the center conductor 5 and the outer conductor 6 are electrically short-circuited via this electrode film. The other end surface 8 opposite to this short-circuit end surface 1 is an open end surface on which no electrode is formed.

A dielectric substrate 2 plate 9 common to each of the resonant elements 21 is disposed in front of the open end surface 8 of each of the resonant elements 21 . On one main surface of the dielectric substrate 9 are patterned electrodes 101 . . . for electrostatically coupling the resonant elements 21 . 102
．． 103 are individually formed for each resonant element 21 . These coupling electrodes 1.0, . 10
2. 103 are electrically conductively connected to the center conductors 5 of the respective resonant elements 21 through the terminals 11. Further, the other one of the dielectric substrate 9
As shown in FIG. 3, each coupling electrode 101 is placed on the back surface.
. . . In this embodiment, a ground electrode 12 is formed as a common resonant frequency adjustment electrode. Note that this ground electrode is connected to each coupling electrode 101, 102. 103 and may be provided separately.

With such a configuration, capacitances Ca are connected in parallel to the resonant elements 21, respectively.

The fundamental resonant frequency of each stage is mainly determined by the distributed constant and parallel capacitance of each resonant element itself. Therefore, if parallel capacitance is provided, the harmonic resonance frequency will not change.
Fundamental resonance frequency decreases.

The resonant element is designed in advance so that this reduced value becomes a desired value. Then, the apparent harmonic frequency is no longer an integer multiple of the lowered fundamental resonance frequency. In other words, even if a frequency component that is an integer multiple of the lowered fundamental resonance frequency is input, resonance does not occur, so that the spurious response characteristics at that frequency are improved.

In addition to the embodiments described above, the present invention can of course be applied to a dielectric coaxial resonator in which a plurality of resonant elements 21 are integrally formed with one dielectric block, as shown in FIG. 4, for example. .

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a dielectric coaxial resonator according to an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram thereof, FIG. 3 is a longitudinal sectional view of the main part of the embodiment, and FIG. The figure is a perspective view of main parts of another embodiment. 21-23... Resonance element, 8... Open end surface of resonance element, 9... Dielectric substrate, 101-103 Coupling electrode,
12... Resonant frequency adjustment electrode. Patent application: Murata Manufacturing Co., Ltd. II/Figure 1112

Claims (1)

[Claims] (1) A plurality of resonant elements arranged in parallel and a dielectric substrate arranged on the open end surface side of each resonant element, and these resonant elements are arranged on one main surface of the dielectric substrate. Electrodes for electrostatic coupling to each other are individually formed for each resonant element, and a resonant frequency adjustment electrode is formed on the other main surface of this dielectric substrate to adjust the harmonic resonant frequency. A dielectric coaxial resonator characterized by a low fundamental resonant frequency without any movement.