GB539686A - Ultra-high frequency radio systems - Google Patents

Abstract

539,686. Electric resonators ; directive wireless systems. STANDARD TELEPHONES & CABLES, Ltd. May 17, 1940, No. 8839. Convention date, June 2, 1939. [Classes 40 (iii) and 40 (v)] [Also in Group XXXVI] An ultra-high-frequency transmitter comprises a tank resonator combined in one structure with a reflector, based on principles described in Specification 392,962, which carries a dipole aerial, a valve being located within the structure, which may also be used for receiving. In the embodiment shown in Fig. 1, the tank resonator comprises part of a conical surface 12 carrying an adjustable condenser plate 18, and a disc 11 carrying a fixed condenser plate 20 and an oscillation-generating valve 24. The plate 20 is insulated from the disc 11, and their mutual capacity couples the resonator to the oscillator 24. The remainder of the conical surface 12 together with the outside of the disc 11 forms a reflector, and a rim 28 carrying a dipole aerial 27 is provided. The structure may be cylindrical instead of conical, Fig. 2 (not shown). The rim 28 may be omitted, and an additional disc may be supported on insulators between the disc 11 and the aerial 27, Fig. 3 (not shown). Two such systems may be assembled back-to-back in a single structure, the two adjustable condenser plates 56, Fig. 4, being integral with the same knob 59 or mounted on axially adjustable tubes, Fig. 7 (not shown). The planes of polarization of the radiation from the two aerials may be at right angles to one another, so that if the system is used in a directional beacon, the plane of polarization distinguishes one side of the beacon from the other. Fig. 5 (not shown) is a diagram of a lumped-impedance circuit equivalent to the two-resonator circuit. A cubical tank resonator may have four conical reflectors for radiating in four directions at right angles, Fig. 8 (not shown). The resonator may comprise two discs 130, Fig. 9, with the oscillator valve 136 in a central tubular casing 134 which joins the discs and may be insulative or. conductive according to the impedance which the resonator is to have. The antennae 142 are carried by insulating supports 138. The two halves of the antenna are connected with one another through a ring 97 embedded in insulating material 99. The coupling between the oscillator valve 24, Fig. 1, and dipole aerial 27 is provided by a coaxial line 88, Fig. 6, which is connected to two points 100 on opposite sides of the electrical centre of the aerial, at such a distance apart that the impedances of line and aerial are correctly related ; thus the aerial is shunt-excited. The grid 82 of the valve is connected to the coupling disc 11, and the anode 81 to a coupling transformer 84.