Helios Remote Sensing Systems, Inc. proposes to design, develop, build, test, and demonstrate a mounted and dismounted low false alarm rate, LPI/LPD radar prototype for through the wall applications. Helios will develop a modular, man-portable Sense-Through-The-Wall (STTW) radar that can quickly detect, locate, and discriminate hidden chambers and concealed individuals. The proposed STTW sensor system will be able to automatically distinguish between a normal space, for example the space between wall studs, and an occupied space to enable the operator to quickly focus their Sensitive Site Exploitation (SSE) operations. Helios will leverage its extensive working knowledge of STTW radar technology and its practical application in the design of the radar. In Phase I, we will design the LPI/LPD STTW radar using our previous experiences with STTW radar applications. In Phase II, we will develop, build, and test a mounted and dismounted RF prototype radar for thru wall applications.