Design and application of dielectrically scaled double-ridged horn antennas for biomedical UWB radar applications

Ultra-wideband sensing begins to play an important role in biomedical diagnostic systems. Promising and relevant applications include remotely monitored vital functions as well as the characterization of tissues and organs. The acquisition of such physiological signatures requires small and radiation-efficient antennas, designed for ultra-wideband frequency operation. We have developed physically small and adjustable double-ridged horn antennas with which we could demonstrate the specific advantages of miniaturized, dielectrically matched sensor elements in a direct mode compared to remote sensor applications. As a logical consequence of these results, we have considered to replace the lossy high-permittivity liquid by low-loss high-permittivity solid ceramic material to improve the degree of miniaturization and the radiation efficiency further. Some unexpected peculiarities related to this approach are discussed.