JPS61139103A - Dielectric resonator - Google Patents

Abstract

PURPOSE:To obtain a good filter characteristic by forming an annular space piercing a dielectric resonator body, which is formed to a columnar or cylindrical shape, in the axial direction of this body and eliminating influences of spurious when this resonator is applied to a filter circuit. CONSTITUTION:In a conductor case 1, a dielectric resonator body 3 formed to a short columnar shape is fixed onto a dielectric substrate 2 and is shielded electrically by the conductor case 1. Annular narrow spaces (g)... piercing the resonator body 3 in the axial direction are formed at prescribed intervals concen trically in the resonator body 3. In this case, influences of spaces (g) upon the resonance frequency can be almost ignored because lines e1 of the electric force of the fundamental mode TE01delta of the resonator are distributed in the peripheral direction of the resonator body 13. Meanwhile, lines e2 of the electric force of spurious of the HE11delta mode are distributed in the diametral direction of the resonator body 3, and therefore, they traverse spaces (g)..., and the reso nance frequency is varied greatly, and the resonance frequency of spurious of the HE11delta mode is shifted to a considerably high frequency relatively to the resonance frequency of the TE01delta mode.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a dielectric resonator used, for example, as a filter.

<Prior Art> Conventionally, as shown in FIG. 5, this type of dielectric resonator has a resonator body 3 composed of a cylindrical dielectric block, and a cylindrical dielectric block surrounding the resonator body 3. A device shielded with a conductor case l is known.

<Problems to be Solved by the Invention> By the way, in such a dielectric resonator, when the fundamental mode of the resonator main body 3 is the T E o 1t mode, there is an HEl near the resonance point in the TEIllt.
It is well known that lt mode spurious appears. For example, when such a resonator is applied to a filter circuit, this HE + + t mode spurious is
It is preferable to shift to a frequency range considerably higher than the resonance point at ol# in order to obtain good filter characteristics.

However, in the conventional resonator having such a cylindrical resonator main body 3, it has been technically difficult to remove spurious signals near the resonance point.

For this reason, it is conceivable to apply a cylindrical resonator to a filter circuit for those having a cylindrical resonator body 3. However, in this case as well, although the HE mode spurious waves can be shifted to a frequency higher than the resonance point to some extent, it is still insufficient to obtain filter characteristics that can be put to practical use.

In view of these conventional problems, it is an object of the present invention to improve the spurious characteristics of a dielectric resonator using the TEo-th mode as described above, for example, and to promote its application as a filter.

Means for Solving the Problems> In order to achieve the above object, the present invention includes a dielectric resonator body formed in a cylindrical or cylindrical shape, and has an axis attached to the dielectric resonator body. It is characterized by the formation of an annular void that penetrates in the center direction.

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

FIG. 1 is a half-cut perspective view of this embodiment, and FIG. 2 is a cross-sectional plan view. In these figures, the dielectric resonator of this embodiment has, for example, T E o + b as a resonance mode.
mode, and includes a metal conductor case l. The conductor case l is formed in a cylindrical shape, and a dielectric substrate 2 such as forsterite or the like, which has a low dielectric constant and has little influence on the resonance system, is disposed at the bottom of the conductor case l. Inside this conductor case l, a dielectric resonator main body 3 formed in a short cylindrical shape is fixed on the dielectric substrate 2 and is electrically shielded by the conductor case l.

The resonator main body 3 is made of, for example, a titanium oxide (Ti[i)-based ceramic material, and the resonator main body 3 is
Small annular gaps g passing through in the axial direction are concentrically formed at predetermined intervals.

In this case, as shown in FIG. 2, T E in the resonator of this embodiment, ? Since the mode electric lines of force e are distributed along the circumferential direction of the resonator body 3, the air gap g...
The effect on the resonant frequency can be almost ignored. On the other hand, HE, t-mode spurious electric field lines et
Since it is distributed approximately in the radial direction of the resonator main body 3, it crosses each of the gaps g..., and the resonant frequency varies greatly for such narrow gaps g... Therefore, the resonant frequency of the spurious in the HE, lt mode is shifted to a considerably higher side relative to the resonant frequency of the T E , . . . modes. This point becomes more noticeable as the dielectric constant of the resonator body 3 increases.

Now, in this embodiment, the resonator body 3 has a dielectric constant εr
When trying to measure the rate of change in the resonant frequency for a dielectric material with a diameter of 38 and the total width of the gaps g... set to 1% of the diameter of the resonator body 3, we found that T E
The rate of change in the resonant frequency of the o + t mode is within about 0.05%, whereas in HE.

The rate of change of the resonant frequency of the eye mode spurious is 5 to 6%.
It was found that the frequency changes greatly and shifts to a higher frequency range.

3 and 4 show other embodiments of the present invention;
The figure is a half-cut perspective view of this embodiment, and FIG. 4 is a cross-sectional plan view. In these figures, the dielectric resonator of this embodiment basically has a short cylindrical shape with a resonator body 3 having a 1:1 through hole 4 in the axial direction at its center. The structure is similar to that of the previous embodiment. That is, the short cylindrical resonator main body 3 is housed in a conductor case l, and annular gaps g passing through the resonator main body 3 in the axial direction are formed concentrically at predetermined intervals. It has become something that has been done. Then, as in the above embodiment, due to the air gap g..., the resonant frequency of the HE, t-mode spurious is shifted to a considerably higher side relative to the resonant frequency of the T E o +t mode. Become. In addition,
The void g may be an air layer, or may be filled with a material having a low dielectric constant that shifts the resonance point of spurious to a high frequency range.

Note that the shape of this conductor case l is similar to that of the dielectric resonator body 3.
The shape is not necessarily limited to a cylindrical shape as long as it shields the surrounding area.

<Effects of the Invention> As described above, according to the present invention, an annular gap is formed in a dielectric resonator body formed in a cylindrical or cylindrical shape in the axial direction thereof. Therefore, for example, in a dielectric resonator using the T E o , t mode, the air gap has almost no effect on the resonance frequency of the T E o + t mode, and the spurious resonance frequency of the HE, , mode. Since only the resonance frequency of the HE, +, mode spurious can be greatly varied, the resonant frequency of the spurious in the HE, +, mode can be changed to the above-mentioned TE.

, the resonant frequency of the mode can be shifted to a considerably higher side relative to the resonant frequency. Therefore, when the dielectric resonator is applied to a filter circuit, it is possible to obtain good filter characteristics without the influence of spurious components.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention, FIG. 1 is a half-cut perspective view of this embodiment, FIG. 2 is a cross-sectional plan view, and FIG.
3 and 4 show another embodiment of the present invention, FIG. 3 is a half-cut perspective view of this embodiment, FIG. 4 is a cross-sectional plan view, and FIG. 5 is a longitudinal sectional front view showing a conventional example. 3... Dielectric resonator body, g... Air gap.

Claims (1)

[Claims] (1) A dielectric resonator comprising a dielectric resonator body formed in a cylindrical or cylindrical shape, and an annular gap passing through the dielectric resonator body in the axial direction of the dielectric resonator body. .