Over the years, many different sensor types have been evaluated in an attempt to satisfy the need to detect and discriminate tactical and strategic targets concealed in foliage or underground. In large measure these early efforts were disappointing because of the lack of appropriate technologies. Today, by taking advantage of commercial off-the-shelf processors, an advanced analog-to-digital (A/D) converter, and lessons learned, a highly capable impulse radar has been designed and assembled to investigate an ultra-wideband (UWB) radar approach for ground penetration (GPEN) radar studies. The testbed consists of several major subsystems that are modular to allow for the evaluation of alternate approaches. The testbed radar subsystem consist of the antenna, the transmitter, the A/D converter, the processor/data storage system, the timing and control assembly, the positioning subsystem, and the operator interface computer. Many of the subassemblies exist as standard 19 inch rackmount units or as VME-compatible printed circuit assemblies. Much of the system operation is controlled by software, allowing easy modifications or other future upgrades. Data collected with this upgraded system will be used for measuring and analyzing the basic phenomenology of radar propagation through the ground and the response of targets, clutter, and targets embedded in clutter. One important aspect of basic phenomenology studies is validation of models with data. Range profiles of synthetic aperature radar (SAR) processed data from the Army Research Laboratory UWB radar is compared to 3D method of moments models for similar targets. In this paper, a mix of canonical and mine-like targets are examined and compared. Comparison between data and models shows some correlation, thus validating the need for further investigation.