GB503428A - Improvements relating to phase displacing systems for oscillatory directional radio transmitters, receivers or the like - Google Patents

Abstract

503,428. Directive wireless signalling. AGA-BALTIC RADIO AKTIEBOLAG. Oct.. 13, 1937, No. 27838. Convention date, Nov. 26, 1936. [Class 40 (v)] Relates to directional systems of the kind in which the effect of a directional aerial 2, 3, Fig. 1, is combined with that of a non-directional aerial 7, the phase of the latter being periodically reversed so that the resulting cardioid field is swung over from the thin-line position 20, Fig. 3b, to the thick-line position 20<1>, to give a concentrated field along the median line X Y. The invention consists in driving the phase-reversing coupling-condenser at a variable instead of a constant speed, so as to produce complementary signals which are free from " clicks " or interfering sounds along the median line: The rotating vanes 12, 13, Fig. 1, connect the aerial first to one end, and then to the other of the inductance coil 6, thus varying the phase of the voltage supplied to or derived from that aerial. The condenser 8...13 is shown in vertical section in Fig. 2b, in series with a coupling condenser 16, 17. The moving plates of the keying condenser are driven by a motor 15, either with an oscillatory motion, or continuously in one direction at variable speed, so that there is a longer "dwell" at one extreme position than in the other. The " dot " and "dash" signals may also be produced by displacing the centre of the fixed condenser plates relatively to the moving plates.