Some examples of the calculation of near-field dependent parameters for aircraft HF antennas

Moment methods are necessarily used for calculation of the characteristics of HF antennas mounted upon aircraft. Whilst it is possible to obtain reasonable estimates of parameters which depend upon the far-field using a relatively coarse discretization of the airframe, this will not generally suffice for calculation of those which are determined by the near-field. Finer discretization is necessary if the latter parameters are to be calculated with acceptable accuracy. The author attempts to give an indication of discretization judged to be adequate in this regard by examining the prediction of some near-field dependent parameters for three generic aircraft types: a helicopter, a fixed-wing aircraft and a variable geometry aircraft. In the examples described, no empirically derived information has been incorporated into the models. Thus the results represent true predictions rather than `postdictions´