2.4 GHz bio‐radar system with improved performance by using phase‐locked loop

This letter presents a novel bio-radar system with phase-locked loop (PLL) for noncontact measurement of vital sign. As the leakage of the phase noise of local oscillator (LO) through antenna is dominant factor for the distances larger than about 30 cm, the performance of a bio-radar system can be improved with the PLL employment. The proposed bio-radar and PLL are implemented by using conventional commercial components, and the measured result shows that the bio-radar system performance is greatly improved with a PLL without any additional digital signal processing. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 2074–2076, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25366