Results of Numerical and Physical Modelling of Airborne Adcock Arrays for VHF DF (Direction Finding) Applications,

This paper describes an attempt to predict the received voltages on a VHF direction finding DF array using the geometrical theory of diffraction and the principle of reciprocity. Once the received voltages are known bearing errors can be predicted from the phase information. The predicted receive mode radiation patterns are compared with a simple model of a C130 Hercules transport aircraft. Further comparison is made with models representing a low-wing jetliner with underwing engines. The latter aircraft models use either a blunt capped cylinder or a sectional cylinder with a emispherical cap and a conic section. The comparison between predicted and measured results are reasonable.