Multifaceted Free-Space Tissue Sensing up to 100 GHz

While sub-5 GHz frequencies provide large penetration depths, their limited spatial resolution motivates the use of broader bandwidths between 6 and 100 GHz to analyze reflections from layered skin and muscle structures. This study investigates penetration losses through porcine skin as a substitute for human tissue, with particular focus on volume scattering and reflectivity from the muscle surface.

Two tissue configurations are considered: one consisting of epidermis and dermis, and another including an additional hypodermis or subcutaneous fat layer. Free-space measurements using a vector network analyzer are compared with established tissue model parameters to validate the estimated propagation losses. Based on the measured skin losses and the radar cross section (RCS) of muscle, the study derives a link-budget framework for muscle sensing and provides foundational principles for biomedical microwave and millimeter-wave sensing.