Ultra Wide Band (UWB) Wireless bio-medical sensors is a promising new application made possible by recent advances in ultra low power technology. Each sensor measures parameters of interest and sends the data in short bursts to a central device. In developing these sensors, detailed knowledge of the communication channel is essential. Moreover, UWB has a wide variety of applications in medical imaging. The aim of this work is to study the interaction of the UWB signals with tissue of human body and develop appropriate channel modelling tools to be used either for communications or for UWB medical imaging. In particular, propagation characteristics of the different tissue will be investigated, with the purpose of providing an insight into precise relation of these quantities to frequency. Beneficiaries will include, at the beginning, the wireless communication and the bioengineering communities, but the real aim is that the results of the proposed research can contribute to the evolution of communication systems which can dramatically change the future of healthcare with many benefits for patients.