Microwave resonant out-of-plane fed elliptical slot antenna for imaging applications

Development of an effective microwave antenna is important issue for nondestructive sensing and imaging applications. Recently a one-shot, rapid and portable microwave imaging system with a PIN diode-loaded resonant elliptical slot has been developed. In this paper a new approach for feeding a resonant slot used in such a systems is considered. It includes coupling the transmitted and received signals into the slot using out-of-plane (perpendicular) microstrip feed. Three feeds are considered, namely; a 90°-bent microstrip-line feed, a microstrip line proximity feed and a direct microstrip line connection to the slot load. The simulation and measured results show that the antenna with the 90° bent microstrip-line feed demonstrates the best radiation and modulation efficiencies.