Doppler - vhf - rotary radio fire

摘要

1416854 Radio navigation; aerials MARCONI CO Ltd 4 June 1974 [16 Aug 1973] 24605/74 Headings H4D and H4A A Doppler VOR beacon comprises a central omnidirectional aerial, a plurality of substantially similar omnidirectional aerials arranged in a ring about the central aerial, means for radiating from the central aerial carrier power modulated by a reference wave, means for sequentially radiating from at least one of the aerials in the ring at least one sideband of a subcarrier amplitude modulation of the carrier to simulate a rotating source. The central aerial has a higher gain towards the horizon, and over a predetermined angle thereabove, than an individual aerial of the ring of aerials. The central aerial may comprise a vertically stacked array of elements, such as omnidirectional Alford loops, and said loops may each be fed with power suitably controlled in amplitude and phase to achieve the higher gain over an elevational range of, for example, 0 to 35 degrees.