Experiments on wideband through-the-wall radar imaging

The Center for Advanced Communications (CAC) at Villanova University has conducted several preliminary through-the-wall imaging experiments and collected real data on different settings behind the wall using a newly-integrated RF instrumentation suite. The full-polarization, 2D aperture data measurements are taken using an Agilent network analyzer, Model ENA 5071B, implementing a step frequency waveform over a 2-3 GHz frequency range. The room imaged is a typical computer lab that has been lined with radar absorbing material. Three different arrangements of the room's contents are considered: empty scene, calibration scene, and populated scene. The empty scene allows measurement of the noise/clutter background and supports coherent subtraction with the other two scenes. The calibration scene contains isolated reflectors that may be used to determine a fully-polarimetric radiometric calibration solution for the experimental system. The populated scene contains a number of common objects such as a phone, computer, tables, chair and filing cabinet. In addition, a jug of saline solution has been added to crudely approximate a human. Each scene is imaged with and without a wall. The wall is composed of plywood and gypsum board on a wood frame. The antennas are mounted on a 2D scanner that moves the antennas along and adjacent to the wall and is controlled by the network analyzer. Two additional antennas are fixed to the scanner frame and act as bistatic receivers. The paper provides a detailed description of the RF system and experimental conditions and provides a quick look at collected data products. The data measurements, technical details on collection instrumentation, auxiliary measurements, and scene truth data will be made available starting in April 05 to download from the Villanova CAC website at http://www.engineering.villanova.edu/cac/TWRI-experiments.