Defocusing loss for a long periodic-fed reflector

The defocusing loss for a reflector which uses a log periodic feed system will be quantified, The defocusing loss occurs because the phase center location of the log periodic varies with frequency; tradeoffs in the feed position will be addressed. Typical parameters indicate the worst case defocusing loss asymptotically approaches 1.9 dB for very large bandwidths. An example illustrates the application of the analysis.