A Shared Aperture FPC-Lens Antenna for Low Cost Small Flying Object-Based Imaging Radar Applications

A shared aperture Fabry-Perot Cavity (FPC)-Lens hybrid dual band high gain antenna is proposed in this article for very low cost Small Flying Object (SFO) based imaging radar implementation. The designed single layer superstrate acts as a highly reflecting surface for FPC antenna and a highly transmitting phase correcting surface for lens antenna. The transmission and reflection properties of superstrate unit cells can be selected independently. A combination of two different types of unit cells is used to increase the transmission phase variation while keeping the reflection band properties intact. A single feed dual band source patch is designed to illuminate the cavity, whose both operating frequencies can also be decided independently. For small frequency ratio and without any complicated feed network, this antenna achieves high gain at both the operating bands. The fabricated prototype antenna provides a measured impedance bandwidth (BW) of 440 MHz and a peak realized gain of 17.3 dBi at X band and a BW of 785 MHz and peak gain of 16.5 dBi at Ku band. The structure is compact, lightweight, offers high gain with high polarization purity at both the frequencies making it suitable for SFO based imaging radar.