Active patch antennas integrated with FETs using coupled transmission lines

A novel idea of controlling the coupled power from a patch antenna to a coupled transmission line at resonant frequency is developed. With FETs serving as active components, an appropriate gap and the coupled line's length adjusted for expected coupling, a compact five-element uniform linear array is designed. A thicker substrate giving stronger coupling is also presented. This design may find applications in active arrays and quasi-optical power combining.