FINITE-DIFFERENCE TIME-DOMAIN ANALYSIS OF HF ANTENNAS ON HELICOPTER AIRFRAMES

In this paper, the finite-difference time-domain (FDTD) method with th e Berenger perfectly matched layer (PML) absorbing boundary condition (ABC) is used to model the radiation characteristics of high frequency (HF) antennas operating in the 230 MHz range on a full-scale helicopt er. The computed input impedance of both antennas is compared with act ual measurements from an operational full-scale helicopter and also wi th measurements on a scale model NASA generic advanced attack helicopt er (GAAH). To study the coupling effects of the helicopter fuselage on the antenna systems, the S-parameters are computed and compared with measurements on the NASA GAAH scale model, Finally, computed gain patt erns are compared with actual in-flight measurements of the antenna sy stems on an operational full-scale helicopter.