Wave transmission lines and networks – Resonators – Dielectric type
Reexamination Certificate
1999-07-19
2002-03-19
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Resonators
Dielectric type
C333S209000
Reexamination Certificate
active
06359534
ABSTRACT:
The present invention relates to microwave resonators, and relates particularly, but not exclusively, to microwave resonators for use in cellular telecommunications.
Microwave resonators have a wide range of applications. In particular, in cellular telecommunications, microwave resonators are utilised in microwave filters, multiplexers and power combining networks.
Microwave cavity resonators are known which include an electrically conductive housing which defines a resonant cavity which supports standing waves at microwave frequencies (typically of the order of 1 GHz). It is difficult to construct such known resonators compactly, which is a considerable drawback in the field of cellular communications, in which it is desirable to reduce as much as possible the physical size of apparatus.
Dielectric resonators are known which can be constructed more compactly than the cavity resonators referred to above. Such resonators generally comprise a hollow cylindrical electrical conductor defining a cavity containing a relatively smaller cylindrical dielectric arranged coaxially and symmetrically within the cavity. The resonator has a resonant frequency in the microwave frequency region for signals transmitted in a direction parallel to the cylinder axes.
Preferred embodiments of the present invention seek to provide a dielectric resonator which can be constructed more compactly compared than the prior art resonators described above.
According to the present invention, there is provided a microwave frequency resonator, the resonator comprising a hollow electrical conductor defining a resonant cavity, and a substantially cubic member located within the cavity and having a high dielectric constant compared with the remainder of the cavity.
By providing a substantially cubic member, this has the advantage of enabling the resonant cavity to support resonances corresponding to microwaves travelling in three mutually orthogonal directions (and having the same resonant frequency), i.e. corresponding to microwaves travelling parallel to the sides of the cubic member, as opposed to a single direction in the case of the prior art dielectric resonator referred to above. This in turn provides the advantage that approximately three times as many resonances per unit volume can be obtained than in the case of the prior art dielectric resonator, which enables a particularly compact construction of the resonator.
In a preferred embodiment, the substantially cubic member is constructed from ceramic material and the remainder of the cavity contains air.
The ceramic material may be ZTS.
The resonator preferably further comprises coupling means for coupling together resonant modes of the resonator corresponding to microwaves propagating across the cavity in mutually orthogonal directions.
In a preferred embodiment, the coupling means comprises at least one electrically conducting loop having ends connected to the hollow electrical conductor, wherein the or each loop lies in a respective plane oriented at substantially 45° to an end face of the substantially cubic member.
The resonator may further comprise signal input means for inputting electrical signals into the resonator.
In a preferred embodiment, the connecting means comprises a loop of electrical conductor connected at one end thereof to the hollow electrical conductor and adapted to be connected at the other end thereof to a coaxial cable.
The resonator preferably further comprises tuning means for tuning the or each resonant frequency of the resonator.
The tuning means may comprise at least one tuning member material having a dielectric constant high compared with said remainder of the cavity and adjustment means for adjusting the spacing between the tuning member and the substantially cubic member.
The tuning member may comprise a disk of the same material as the substantially cubic member and connected to the hollow electrical conductor by means of an electrical insulator.
In a preferred embodiment, the cavity is substantially cubic and the substantially cubic member is arranged in the cavity with faces thereof extending substantially parallel to the adjacent faces of the hollow electrical conductor.
The resonator preferably further comprises support means for supporting the substantially cubic member in the cavity.
In a preferred embodiment, the support means comprises a first dielectric member arranged between a face of the substantially cubic member and the adjacent face of the hollow electrical conductor.
The support means preferably further comprises a second support member arranged between a face of the substantially cubic member and the adjacent face of the hollow electrical conductor and on an opposite side of the substantially cubic member to the first support member.
The support means may further comprise urging means for placing the substantially cubic member under compression between the first and second support members.
The first and/or second support members are preferably formed substantially from alumina.
According to another aspect of the invention, there is provided a microwave frequency bandpass filter, the filter comprising signal input means for inputting electrical signals into the filter, signal output means for outputting electrical signals from the filter, and at least one resonator as defined above connected between the signal input means and the signal output means.
The filter may comprise a plurality of said resonators electrically coupled together.
According to a further aspect of the invention, there is provided a microwave frequency bandstop filter, the filter comprising a 3 dB hybrid, and a bandpass filter as defined above connected between a first pair of terminals of the hybrid such that the transmission response between a second pair of terminals of the hybrid represents the reflection coefficient of the bandpass filter.
In a preferred embodiment, an even mode impedance of the bandpass filter is connected to one terminal of said first pair and an odd mode impedance of the bandpass filter is connected to the other terminal of said first pair.
The hybrid may comprise a microstrip coupler.
According to a further aspect of the invention, there is provided a microwave frequency power combiner, the combiner comprising amplifier means for inputting a plurality of electrical signals at different frequencies into at least one resonator as defined above, and output means for outputting electrical signals from the or each resonator to a microwave frequency antenna.
REFERENCES:
patent: 2890421 (1959-06-01), Currie
patent: 4489293 (1984-12-01), Fiedziuszko
patent: 4521746 (1985-06-01), Hwan et al.
patent: 5233319 (1993-08-01), Mizan et al.
patent: 5638037 (1997-06-01), Kurisu et al.
patent: 6072378 (2000-06-01), Kurisu et al.
patent: 552 304 (1974-07-01), None
patent: 37 06 965 (1987-09-01), None
patent: 0 064 799 (1982-11-01), None
patent: 0 432 729 (1991-06-01), None
patent: 2 284 311 (1995-05-01), None
patent: 59 198003 (1984-09-01), None
patent: 87 00350 (1987-01-01), None
Hunter, et al., “Triple Mode Dielectric Resonator Hybrid Reflection Filters”,IEEPAug., 1998.
Patent Abstracts of Japan, vol. 9, No. 56 (E-302) '1779!, Mar. 12, 1985.
Awai I et al., “A Dual Mode Dielectric Waveguide Resonator and Its Application to Bandpass Filters,” IEICE Transactions on Electronics, vol. E78-C, No. 8, p. 1018-1025, Aug. 1, 1995.
Filtronic Plc
Glenn Kimberly E
Madson & Metcalf
Pascal Robert
LandOfFree
Microwave resonator does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Microwave resonator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Microwave resonator will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2838070