Metamaterial Antennas for RADAR and SAR

RADAR and Synthetic Aperture Radar (SAR) systems require broadband directive antennas. Directivity requires antennas to be large, which turns out to be impracticable in many applications. This work presents a combination of an array of Vivaldi antennas with a slot ring resonator metamaterial for SAR applications. As such, vertically and horizontally polarized Vivaldi antennas can be simultaneously used for transmission and reception, allowing the use of lower transmission power with higher temporal duration signal instead of emitting high power pulses for short instants. The prototype at 2.3 GHz band is etched on an FR4 substrate and is fabricated and measured, obtaining similar results between simulation and measurements. Measured results show that, at 2.3 GHz, the metamaterial correctly transforms a linear polarization into a circular one while the array gain obtains its maximum. The proposed array allows for a more compact and easy-to-use test platform, being a valuable solution for SAR systems.