Retrodirective array tracking prediction using active element characterisation

The authors report on the comparison between the measured and predicted mon ostatic radiation pattern of a four-element retrodirective array (RDA) oper ating at 1GHz. Predictions of array performance were carried out using an i solated element approach then an active element approach. Classical modelli ng of the RDA performance yielded a worst-case amplitude error with respect to measurement of 3.7 dB at 50 degrees From boresight while an adapted mod el presented which allows active element pattern incorporation yields an er ror of only 0.5dB at 50 degrees. In addition, the individual active pattern characterisation approach allows for the first time a rationale for why me asured RDA tracking capability is better than previously established theore tical prediction.