Thinned stepped frequency waveforms to furnish existing radars with imaging capability

Introducing imaging capability to an existing radar, even if it is a high RF bandwidth radar, may be difficult, due to limitations on the IF bandwidth, limitations on the pulse repetition frequency and electromagnetic compatibility problems. This paper discusses the use of thinned stepped frequency waveforms, which enable the radar to switch between RF frequencies to provide a synthesized wide RF bandwidth, while the thinning may alleviate some of the constraints imposed on the radar. Random and periodic thinning are discussed in the first part of this paper. However, thinning may cause degradation in image quality, thus an additional technique - Sequence CLEAN deconvolution - is suggested. Sequence CLEAN is an iterative deconvolution algorithm, adopted from the field of Radio Astronomy, which is capable of resolving close targets in a dense environment, where the system response is heavily affected by high sidelobes.