Several techniques for the measurement of elevation angles of radio signals in the h.f. band with a vertical array of aerials are described. These include the Wilkins-Minnis method, null-selection and elevationscanning techniques, and a method of wavefront analysis in which the amplitudes and phases of the aerial signals are measured. Aircraft calibrations have been used to check some of the methods.
1Principal symbols a = ground slope A = elevation angle A = wavelength (f> = signal phase shift 6 = angle on cathode-ray tube E = incident field strength / = frequency, MHz h = height of aerials S = aerial signal strength
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