Wave transmission lines and networks – Resonators – With tuning
Patent
1996-06-04
1997-10-14
Lee, Benny T.
Wave transmission lines and networks
Resonators
With tuning
3332191, H01P 710
Patent
active
056776535
DESCRIPTION:
BRIEF SUMMARY
This application claims benefit of international application PCT/F195/00547, filed Oct. 4, 1995, published as WO96/11511 Apr. 18, 1996.
BACKGROUND OF THE INVENTION
The invention relates to a dielectric resonator comprising a dielectric body having at least one planar surface, a frequency controller comprising an adjustment mechanism and an electrically conductive adjustment plane, which is substantially parallel with the planar surface of the dielectric body and movable by means of the adjustment mechanism in the perpendicular direction with respect to the resonator discs for adjusting the resonance frequency by changing the distance between the adjustment plane and the planar surface of the dielectric body, and an electrically conductive casing.
Recently, so-called dielectric resonators have become more and more interesting in high frequency and microwave range structures, as they provide the following advantages over conventional resonator structures: smaller circuit sizes, higher degree of integration, improved performance and lower manufacturing costs. Any object which has a simple geometric shape, and the material of which exhibits low dielectric losses and a high relative dielectric constant may function as a dielectric resonator having a high Q value. For reasons related to manufacturing technique, a dielectric resonator is usually of a cylindrical shape, such as a cylindrical disc.
The structure and operation of dielectric resonators are disclosed e.g. in the following articles: Siemens Components XXIV (1989) No. 5, p. 180-183. Journal, September 1986, p. 189-189. Microwave Circuits", Marian W. Pospieszalski, IEEE Transactions on Microwave Theory and Techniques, VOL. MTT-27, NO. 3, March 1979, p. 233-238.
The resonance frequency of a dielectric resonator is primarily determined by the dimensions of the resonator body. Another factor that has an effect on the resonance frequency is the environment of the resonator. By bringing a metallic or any other conductive surface to the vicinity of the resonator, it is possible to intentionally affect the electric or magnetic field of the resonator, and thus the resonance frequency. In a typical method for adjusting the resonance frequency of the resonator, the distance of a conductive metallic surface from the planar surface of the resonator is adjusted. One prior art dielectric filter design of this kind is shown in FIG. 1, in which a resonator comprises inductive coupling loops 5 (input and output), a dielectric resonator disc 3 installed in a metal casing 4 and supported by a dielectric leg 6, and a frequency controller attached to the metal casing 4, comprising an adjustment screw 1 and a metal plane 2. The resonance frequency of the resonator depends on the distance L between the resonator disc 3 and the metal plane 2 in accordance with a graph in FIG. 2.
As appears from FIG. 2, frequency adjustment is based on a highly accurate mechanical movement, the slope of adjustment k also being steep. When the resonance frequency becomes higher, e.g. to the range 1500-2000 MHz or higher, the dimensions of the basic elements of the dielectric filter, such as those of the resonator disc 3 or the adjustment mechanism 1,2 are reduced. As a result, adjusting the resonance frequency of a dielectric resonator with prior art solutions sets very high demands on the frequency adjustment mechanism, which, in turn, increases the material and production costs. In addition, as the mechanical movements of the frequency adjustment device must be made very small, adjustment will be slower.
SUMMARY OF THE INVENTION
The object of the invention is to provide a dielectric resonator providing a higher adjustment accuracy and speed.
This is achieved with a dielectric resonator, which is characterized in accordance with the invention by the frequency controller further comprising cylindrical supporting block gliding telescopically along friction surfaces inside the first block, second cylindrical supporting block, and adjustment mechanism and arranged to be located in the center h
REFERENCES:
patent: 4019161 (1977-04-01), Kimura et al.
patent: 4565979 (1986-01-01), Fiedziuszko
Lee Benny T.
Nokia Telecommunications Oy
Summons Barbara
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