Wave transmission lines and networks – Resonators – Dielectric type
Patent
1996-06-04
1998-01-27
Pascal, Robert
Wave transmission lines and networks
Resonators
Dielectric type
333235, H01P 710
Patent
active
057126062
DESCRIPTION:
BRIEF SUMMARY
This application claims benefit of international application PCT/FI95/00548, filed Oct. 4, 1995.
BACKGROUND OF THE INVENTION
The invention relates to a dielectric resonator comprising a cylindrical dielectric resonator body comprising a concentric cylindrical recess; a frequency controller comprising an adjustment screw and a second cylindrical dielectric adjustment body, which is movable by means of the adjustment screw in the axial direction within the recess in the resonator body for adjusting the resonance frequency; 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 some 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. The resonance frequency varies as a non-linear function of the adjustment distance. Due to this non-linearity and the steep slope of adjustment, accurate adjustment of the resonance frequency is difficult and demands great precision. Furthermore, an unloaded Q value varies as a function of the distance of the conductive plane.
It is possible to keep the Q value constant and achieve more linear frequency adjustment in a wider range by bringing another dielectric body to the vicinity of the resonator body instead of a conductive adjustment plane. In this case, too, the adjustment curve is still steep. 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 body 3 in a metal casing 4 and supported by a dielectric or isolating leg 6, and comprising a concentric cylindrical recess 7. The resonator further comprises a frequency adjustment mechanism comprising an adjustment screw 1 and a dielectric cylindrical adjustment body 2, which is movable by means of the adjustment screw 1 in the axial direction inside the recess 7 of the resonator body 3 for adjusting the resonance frequency. The resonance frequency of the resonator depends on the distance L between the bottom of the recess 7 of the resonator body 3 and the bottom surface of the adjustment body 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 body 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 th
REFERENCES:
patent: 4728913 (1988-03-01), Ishikawa et al.
Nokia Telecommunications Oy
Pascal Robert
Summons Barbara
LandOfFree
Dielectric resonator having adjustment bodies, for making fast a does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Dielectric resonator having adjustment bodies, for making fast a, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dielectric resonator having adjustment bodies, for making fast a will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-345495