Analyzing Receiver Bandwidth for Near-Range Ultra-wideband Pulse Compression Imaging Radar Systems

During recent years of developing a near-range ground-penetrating radar for explosive hazard detection, researchers at the U.S. Army Combat Capabilities Development Command Army Research Laboratory have been focused on developing receiver design parameters that optimize system performance. In general, a radar designer often aims to reduce the bandwidth of a receiver because it will result in a reduction in noise floor and analog-to-digital converter requirements. However, if receiver blanking is employed (i.e., the process of pulsing transmission and reception so that they do not occur simultaneously), the system's chosen bandwidth can negatively impact the effectiveness of receiver blanking. That is to say, the step response of the system (which approximately occurs during the receiver turn-on stage) is dictated by the receiver's bandwidth. The response can be characterized by its delay and, more importantly, by its rise (or fall) time. The rise and fall time can manifest in a smearing (or ramping) at the near and far boundaries of the illuminated scene of interest. This could lead to missed detections of close-in or far-out targets. The aforementioned is discussed in detail, and the ramifications on near-range synthetic aperture radar image formation is presented.