Detection of Targets Behind Walls Using Ultra-Wideband Short Pulse

Abstract

Impulse radar can be used to detect the presence and movement of targets behind walls. To be an effective detection system, the radar should have the transmitted signal at a frequency low enough to be able to penetrate walls and have a very wide bandwidth so that targets behind walls are clearly identified. Bandwidths need to be several gigahertz to achieve high resolution of the order of a fraction of a meter. An ultra-wide band (UWB) radar system satisfies these low frequency and large bandwidth requirements. UWB radars are defined as those for which the relative bandwidth is equal or greater than 25%. The UWB transmitted pulse usually consists of a very short pulse train of just a few cycles. The EM scattered fields from a target, illuminated by the UWB radar, are received at several locations and then processed to construct their corresponding images. UWB radar systems have been used for a wide variety of civilian and military applications. M. Skolnik et al.1 outlined considerations that characterize the design of UWB radar for the detection of low-altitude missiles over the sea. He discussed the factors that enter into the choice of frequency, the selection of the type of the transmitter, antenna, and the receiver as well as signal processing issues. UWB for minefield detection (ground penetrating radars) was also investigated by L. Carin et al.2, where a full-wave model for EM scattering from buried targets is developed. Such systems were also studied thoroughly by E. K. Walton and his group at the Ohio State University Electro Science Laboratory3.