Radar range improvement using gradient-free optimization for health care applications

Frequency-stepped continuous wave (FSCW) radars have been recently investigated in health care aiming at contactless health monitoring. The mono-static radar architecture is of particular interest due to its low cost. However, monostatic radars suffer from the leakage between the transmitter and receiver paths, which can drastically reduce the detection range of the radar. This paper proposes the DIRECT optimization algorithm for determining the voltages controlling the leakage canceler. The method allows to efficiently calibrate the leakage canceler, which in turn resulted in the leakage amplitude reduction with a factor of 127.4 in average with around 128 measurements per frequency.