A Broadband Microstrip Antenna With Improved Gain for Noncontact Vital Sign Radar Detection

A 4.37 GHz broadband microstrip antenna with improved gain was designed and fabricated. Compared to a partial ground plane single-patch reference antenna, the proposed broadband antenna shows better directivity and improved gain performance. In addition, its radiation pattern was designed for a vital sign radar application. This antenna was implemented in a portable 4.46.7 GHz radar sensor, which can be used for noncontact vital sign detection for security or healthcare applications. The wide frequency tuning range allows the system to be tuned for an optimum transmission frequency.