GB454572A - Improvements in or relating to electrical resonators and to electrical wave filters for use in high frequency signalling and like systems - Google Patents

Abstract

454,572. Resonator units. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Electra House, Victoria Embankment, London.- (Assignees of Peterson, H. 0.; Riverhead, Long Island, New York, U.S.A.) April 2, 1935, No. 10242. Convention date, April 2, 1934. [Classes 40 (iii) and 40 (v)] A bottle-shaped ultra-high-frequency resonator equivalent to a tuned circuit but having a low power factor consists of an outer cylinder 4 constricted at 10, and an inner cylinder 2, joined at their ends by an annulus 6 and provided with connecting-leads 28. The inherent capacity and inductance of the system causes resonance at a frequency such that the length of the cylinders is somewhat less than a quarter-wave-length. The resonators are rigidly mounted and may be located in hermetically sealed containers under thermostatic temperature-control, or in evacuated containers inside thermostatic boxes. Condensation of moisture may be avoided by keeping the resonators above the ambient temperature. The interior of the resonator may be filled with low-loss dielectric such as sulphur or pure water, or the inner surfaces may be covered with mica. Expansion with temperature may be prevented by rigid supports 18, 20. The cylinders 2, 4 may be of circular or other section. The Specification as open to inspection under Sect. 91 comprises also the following subject-matter: Ultra-high-frequency resonators. The parts 2, 4, may be straight cylinders. A condenser may be connected in shunt or in series with the system. A portion of the outer cylinder may be constricted or a portion of the inner tube may be expanded to give a lumped capacity. The inner conductor may be shaped like a dumb-bell as at 154, Fig. 12 (Cancelled), or the system may form a closed surface and the inner part may have a head 16, Fig. 13 (Cancelled). This arrangement ensures that the variation of resonance frequency with temperature shall be small : and such a result can be enhanced by providing the ends 14, 16 with interleaved corrugations. With the same object the resonator may be constructed of invar. The resonator may be tunable by means of a sliding metal ring 184, Fig. 13 (Cancelled). The capacity may be adjusted by means of an interior rotatable wing. The inner cylinder 2 is preferably hollow but may be solid. Wireless circuits employing resonator units. The resonators described above may form the tuned elements of a push-pull heterodyne or homodyne receiver, the frequency being adjustable as shown in Fig. 13 (Cancelled), or of the grid and plate circuits of a generator which oscillates in virtue of its internal capacity : or of a back-coupled generator with screen grid, or of a generator wherein oscillations are maintained by reaction between the grids ; or of a push-pull oscillator with inter-electrode feed-back, Fig. 12 (Cancelled), where the anode tuning-circuit 168 as well as the input circuit may comprise a resonator of the type shown at 150 ; or of the input circuit of a valve, Fig. 13 (Cancelled), whose output circuit is tuned by Lecher wires 196, the polarity of the electrodes being such as to produce either inter-electrode feed-back or a Barkhausen-Kurz effect. The invention may also be applied to magnetron oscillators. The resonator may itself provide the feed-back in a screen-grid oscillator. Wave filters. Resonators constructed as described above may form the shunt arm of an ultra-high-frequency band-pass filter, whose series arms comprise condensers. Alternatively, filter arms may comprise Lecher wires 101, Fig. 20a (Cancelled). These wires function as a series-tuned circuit, a parallel-tuned circuit, or an inductance, according to their length and to whether their ends are opencircuited or short-circuited. Filter arms may alternatively comprise coaxial cylindrical conductors 111, Fig. 20a (Cancelled), whose length bears a definite relation to the frequency-range for which the filter is designed. The filter sections may be shielded or earthed and may include condensers. Various types of filter can be built up by variously combining elements of the above kind, the lengths of these being equal to half, a quarter, or less than a quarter of the wave-lengths of the frequencies by which the filters are characterized. The subject-matter of the preceding three paragraphs does not appear in the Specification as accepted.