Wave transmission lines and networks – Resonators
Patent
1989-06-12
1991-09-10
LaRoche, Eugene R.
Wave transmission lines and networks
Resonators
333202, H01P 700, H01P 120
Patent
active
050477390
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a resonator structure comprising a helix resonator wound of metal wire into a cylindrical coil and supported by a plate of insulating material disposed therewithin.
Various coils and capacitors are used widely as basic structural parts in electrotechnical filters With frequencies of the order of hundred megahertz, losses begin to grow as well as side effects caused particularly by the structure of capacitors. The series inductance of a capacitor is no longer an insignificant matter nor is the stray capacitance between the coil turns relative to the surroundings. Up to a certain limit, such problems can be reduced by capacitor and coil structures. However, with increased frequencies the losses of coils and capacitors increase in the end to such an extent that various transmission line and cavity resonators are the only alternative as far as losses are concerned.
Having small losses, coaxial resonators are the most widely used especially with great powers. The losses decrease with increasing resonator size and simultaneously the power resistance is improved. At frequencies up to about 10 to 15 GHz, strip and microstrip techniques are used widely.
Within the frequency range from 100 to 1000 MHz, both coaxial and strip line resonators are often unnecessarily large as well as expensive. Within this frequency range, so called helix resonators are in general use. The structure of helix resonators differs from that of coaxial resonators in that the middle wire is wound into a coil. The specific impedance of a helix resonator is mainly determined by the ratio of the diameter of the coil to the inner dimension of the outer shell and the pitch of the coil. Within the frequency range from 100 to 1000 MHz and the Q value range from 500 to 1000, the size of a helix resonator is about one third of that of a coaxial resonator with similar properties. The helix resonator is usually made in the form of a cylindrical coil and supported by disposing within the coil a frame manufactured of a ceramic or plastic material in various ways. This is necessary for achieving a sufficient mechanical strength. However, the structure is thus difficult and expensive to manufacture in series production, especially with small resonator sizes.
In portable radio devices in particular, small-size resonators with small losses are of vital importance as structural parts in various high-frequency filters. When the size has become smaller, it has become increasingly difficult to at all attain a sufficient manufacturing accuracy in the production of such filter structures even though expensive solutions were used.
The object of the present invention is to provide a resonator structure which is well suited for series production due to its easy and inexpensive manufacture and which, however, combines the advantages of a good volume/loss ratio of a helix resonator and a simple small-loss support structure. This is achieved by means of a resonator structure of the type described at the beginning in such a way that at least part of the insulating plate comprises an electrical circuit formed by strip lines, and that the helix resonator is connected electrically to said circuit.
The basic idea of the invention is thus to integrate a discrete helix resonator in a strip line structure in such a way that the insulating plate on the surface of which the strip line structure is formed functions simultaneously as a support for the helix resonator.
In the structure according to the invention a good reproducibility and mechanical simplicity are obtained, which improves the productive capacity and reduces costs. Circuit technical solutions which have not been used previously on account of problems of reproduction are now possible, which improves the efficiency of the products.
According to a preferred embodiment of the invention, the housing surrounding the resonators is formed by two halves made of metal or coated with metal so as to be electrically conductive. The halves are positioned against one another and interconnected in an electri
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patent: 3691487 (1972-09-01), Yoshimoto
patent: 4342969 (1982-08-01), Myers et al.
patent: 4621245 (1986-11-01), Dobrovolny et al.
patent: 4682131 (1987-07-01), May
patent: 4700158 (1987-10-01), Dorsey
Patent Abstracts of Japan, vol. 9; No. 302(E-362), abstract of JP 60-140901, published 1985-07-25.
Patent Abstracts of Japan, vol. 9; No. 169(E-328), abstract of JP 60-42902, published 1985-03-07.
Ham Seung
LaRoche Eugene R.
LK-Products OY
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