The prediction of HF antenna performance on helicopters using NEC

It is of practical relevance to be able to calculate antenna properties which depend upon the near-field as well as those which depend upon the far-field. A study performed by the writer, of the estimation of some of these quantities for two helicopters using numerical electromagnetics code (NEC) is outlined. The two helicopters studied were both fitted with loop (ie. magnetic dipole) antennas. The first was fitted with two antennas mounted upon diametrically opposite sides of the tail cone, and the second fitted with one antenna mounted on left-hand side of the rear cabin area. An attempt has been made to compare the results of these computations with experimental measurements (radiation patterns) performed upon both real and scale model aircraft, and with independent calculations of some near-field quantities