Impact of elevation angle variations in wideband adcock direction finders subject to mutual coupling

This paper describes how variations in elevation angle of incoming signals can affect the accuracy of Adcock direction finders (ADFs) in estimating the azimuth direction of arrival (DOA). In accordance with Adve and Sarkar [2000], Maxwellpsilas equations are solved to calculate the mutual coupling characterizing a typical ADF. The voltages at the antenna elements are calculated under several plane-wave excitations that vary both in azimuth and elevation, and processed following two different ADF techniques. The first technique, the Adcock Watson-Watt direction finder (AWWDF), is based on the processing of relative amplitude measurements, while the second technique, the Adcock Butler matrix direction finder (ABMDF), is based on the processing of relative phase measurements. The DOA estimates obtained using the two techniques are finally compared and the possibility of applying a correction to the raw estimates in order to improve the accuracy is evaluated. Contrary to the theory of operation of ADFs, it is found that the elevation angle has an impact on DOA estimation accuracy due to mutual coupling..