Radio frequency and quasi-DC mathematical modelling for the assessment of an aircraft HF antenna system

A study of a particular airborne antenna system is described in which the prediction of the terminal reactance, as presented to the antenna tuning unit, is attempted across the HF band. Two models are considered necessary for this purpose, neither of which incorporates empirically derived information. Both models are described and each uses the method of moments. The results produced by the radio frequency (RF) model employed for the antennas and airframe are supplemented by those of a quasi-DC model which is used to calculate the stray reactances associated with the configuration of the terminals inside the aircraft. The RF model has a very high sampling density and uses NEC as the solution code. Some possible sources of error associated with each model are considered, and the results of the calculations compared with experiment. It is concluded that the accuracy attained is sufficiently good for engineering purposes