Elevation Angle of Arrival Measurement with a Circularly Disposed Antenna Array.

Recent studies have indicated that it is possible to find the elevation angle of arrival of distant signals using a CDAA. However, only a limited amount of experimental work has been done to determine which method or methods are most reliable for doing this. This thesis is primarily an experimental study comparing two methods for determining elevation angle with a CDAA system Wullenweber. One method is the phantom method, which is based on phase comparison between existing Wullenweber antennas. The other is the amplitude comparison method for this, the ratio of signal amplitudes from a pair of vertically stacked horizontal dipoles yields the necessary information. An experiment was devised to simultaneously gather signal information from the phantom and the dipole antennas and then record the data on magnetic tape. The tape was further processed to yield the elevation angles for the two methods. Several important conclusions were drawn from the study. 1 The phantom method, as implemented, is sensitive to noise. Regions are self consistent only if signals are greater than 1000 microvolts. 2 In areas of greatest signal strength, all phantoms gave results which were alike and physically realistic. In previous studies, the angles were often different and too high. 3 The amplitude method seemed less sensitive to noise, but yielded angles consistently higher than expected. For periods of maximum signal strength, the elevation angles determined by the amplitude method paralleled those given by the phantom method, but were approximately 10 deg higher. Author