GB1515710A - Radio receiving antennae - Google Patents

Abstract

1515710 Omnidirectional antenna system MARCONI CO Ltd 17 June 1976 [24 Sept 1975] 39203/75 Heading H4A A loop antenna radio receiving system has two loop antennae 1, 2 which are cross-mounted (see Fig. 1) and means 5, 6 for subjecting the signals received by one loop to a 90‹ phase shift compared with signals received by the other loop prior to combining so as to make the system relatively insensitive to the direction of an arriving wave. The outputs of loops 1, 2 are supplied by way of wideband transformers Tl, T2 to phase-shifting RC networks 5, 6, the outputs of these networks being supplied to cathode followers V1, V2 after which the signals are combined and supplied by way of coax 7 to a remote receiver. Amplifying valve (V3), (V4), (Fig. 3, not shown) may be introduced between the wide-band transformers and the RC networks, or alternatively between the RC networks and the cathode followers. Equivalent transistor circuits may be used. The gain of the amplifiers may be arranged to drop at higher frequencies so as to compensate for the effect of frequency on the effective height on the loops. The shape of the loops may be for example circular, square or (as shown) triangular, but both must be similar.