DE2810799

1536996 Radio direction-finders PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 25 March 1977 12628/77 HÚading H4D In a radio source direction-finder, a circular array of N equally spaced omnidirectional aerial elements in a horizontal plane affords a plurality of interferometric pairs (either between a common element C and each of the other elements 1 ... N, or between adjacent pairs of elements, or between pairs of elements spaced from each other by other elements), a series of phase discriminators U each associated with a respective pair of elements yield a phase-difference measurement in digital form, and digital logic means XPL derives a point of zero phase around the circular array from which the bearing of the radio source is obtained. There is inherent immunity to reflection errors because of the rotational symmetry of the circular array. The method involves the derivation of sinusoidal phase graphs (see particularly Figs. 2, 3, 8 and 9 (not shown)).