Ultra-wideband (UWB) radar enables detection and imaging of electrically contrast dielectric and conducting objects inside the human body that can be used to detect tumors, internal wounds and support other medical diagnosis along with mapping different metal/dielectric inclusions to navigate, e.g. a robotic surgical tool. General principles to design such systems and their building blocks are discussed along with implementation challenges. Two biomedical test radar systems are described to illustrate the study.