JPS6029204Y2 - coaxial resonator - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a coaxial resonator, and in particular, to a one-wavelength coaxial TEM resonator in which a dielectric material is interposed between an inner conductor and an outer conductor.

Filters conventionally used in the VHF band or UHF band include those using a pressure resonator and those using a coaxial resonator.

However, the former does not have sufficient selectivity characteristics,
The latter had the disadvantage of being large.

Recently, in the field of communication equipment, there has been a demand for smaller and lighter systems, and while other parts are being made smaller and lighter, they are still used in large numbers due to their importance. Since filters are difficult to make smaller and lighter, they have been a cause of delays in reducing the size and weight of systems.

Therefore, reducing the size and weight of such filters has been a top priority for engineers in this field.

Therefore, the present inventors developed a four-wavelength coaxial TEM resonator in which a dielectric material is filled between an inner conductor and an outer conductor.

Since such a dielectric coaxial TEM resonator can be made compact, it has an extremely large advantage in reducing the size and weight of the filter and therefore the entire system.

However, such a single-wavelength coaxial TEM resonator filled with a dielectric material has a high Q power, so it is easy to excite harmonic components such as 3 times or 5 times, which are difficult to avoid in a 4-wavelength resonator. Third harmonic resonance occurs as spurious.

On the other hand, in general transmitters, etc., the active elements always generate harmonics of double or triple harmonics, and if a j-wavelength axis TEM resonator filled with a dielectric material as described above is used, it is possible to eliminate such harmonics. Due to the characteristics, the third harmonic is generated as a spurious wave.

Therefore, the main purpose of this invention is to provide a coaxial resonator which can improve spurious characteristics of harmonics while eliminating the above-mentioned problems.

In summary, this invention is based on a j-wavelength axis TEM resonator in which a dielectric is inserted between an inner conductor and an outer conductor, in which a part of the short-circuited side of the dielectric is separated from the other part of the dielectric. This is a coaxial resonator constructed from a solid dielectric material with a relatively low dielectric constant, and whose resonance characteristics are shifted to improve spurious characteristics.

The above objects and other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

FIG. 1 is a diagrammatic cross-section 1 showing an embodiment of this invention. It is a diagram.

In the configuration, each of the four wavelength coaxial TEM resonators 1.1 includes an inner conductor 11, an outer conductor 12, and a dielectric 13 filled between the inner conductor 11 and the outer conductor 12.

This four-wavelength coaxial TEM resonator 1 is manufactured by baking a material, such as silver paste, which has good high frequency characteristics and good adhesion to the dielectric material, on the inner and outer peripheral walls of the dielectric material 13, and It is formed as an outer conductor 12.

This dielectric 13 is preferably made of a ceramic material, but if the conductors 11 and 12 are made of silver in order to reduce loss, the firing temperature of silver is 600 to 900°C, so it is necessary to use a material that can withstand this temperature. This is because it becomes a condition.

Of course, if the conductors 11, 12 are not formed by baking silver, the dielectric 13 may be made of another material.

Further, an electrode 3 for dielectric coupling is inserted between one end of each of the dielectrics 1, ie, the short-circuit side end faces.

That is, the two four-wavelength coaxial TEM resonators 1, 1 are inductively coupled by the electrode 3 having the inductive coupling window 31 at each short-circuited end face.

It goes without saying that the coupling state is also controlled by the size of the inductive coupling window 31.

In such a coaxial resonator, the dielectric material 13a on the coupled short-circuit side has a dielectric constant smaller than that of the dielectric material 13 in other parts.

For example, false light can be used as this dielectric 13a.

According to the above configuration, the electric field of the fundamental wave is O or close to 0 on the short-circuit surface side of the resonator, so even if the dielectric constant of the dielectric 13a is low, the influence on the resonant frequency is small, but the third harmonic Since the electric field of the wave is also large on this short-circuited side of the resonator, the effective permittivity decreases significantly and its influence on the resonant frequency becomes extremely large.

In other words, the third
Harmonic resonance will occur in the higher frequency range.

The resonant frequency of a resonator with such a structure is Q='1tanθ1+layer anθ2 (1−tan2θ1) tan3coffinβ1=β111. β2=β212= ・ ・β1β
1 11 Da・4・β1 111 However, β1 is the electrical length of the dielectric 13, and β2 is the dielectric 13a.
, β1 is the wavelength constant of the dielectric 13, β2 is the wavelength constant of the dielectric 13a, 11 is the geometric length of the dielectric 213, 100 is the geometric length of the dielectric 13a, and El is the dielectric of the dielectric 13. E2 is the dielectric constant of the dielectric 13a.

FIG. 2 is a graph showing the characteristics of this embodiment.

The horizontal axis of the graph in FIG. 2 is 12/211+12, and the vertical axis shows the frequency according to the pet dog.

Further, curve A shows the characteristics of the fundamental wave, and curve B shows the characteristics of the third harmonic.

As is clear from this figure, as the length of the dielectric 13a increases, the resonator wave number of the third harmonic increases rapidly, but the fundamental resonance frequency hardly increases.

It goes without saying that the length of the dielectric 13a should be selected within this range.

In addition, as a result of the experiment, the Q of the resonator 1 at this time did not change at all compared to the case where the dielectric constant was constant over the entire length.

As described above, according to this invention, in a long wrinkled coaxial TEM resonator in which a dielectric is inserted between an inner conductor and an outer conductor, a part of the short-circuited side of the dielectric is set relative to the other part. Since the structure is made of a solid dielectric material with a low permittivity, the frequency of the third harmonic resonance (excitation), which is characteristic of a wavelength-coaxial TEM resonator, shifts to a high range that does not pose a problem in practical use, so its spurious characteristics are significantly reduced. It can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of this invention. FIG. 2 is a graph showing changes in the fundamental resonant frequency and the third harmonic resonant frequency when the length of the low permittivity dielectric portion occupying the resonator length in this invention is changed. In the figure, 1' is a j-wavelength coaxial TEM resonator, 11 is an inner conductor, 12 is an outer conductor, 13 is a dielectric, and 13a is a low dielectric constant dielectric.

Claims (2)

[Scope of utility model registration request] (1) An 11-wrinkle-long coaxial TEM resonator including an inner conductor, an outer conductor, and a dielectric interposed between the inner conductor and the outer conductor, wherein a part of the short-circuit side of the dielectric, the dielectric A coaxial resonator characterized by being constructed of a solid dielectric material having a relatively lower dielectric constant than other parts of the body. (2) The coaxial resonator according to claim 1 of the utility model registration claim, wherein the part is determined within a range that does not affect the fundamental number.