A Dual-Band Patch Antenna Employing a Folded Probe Feed for Nonlinear Radar Applications

In this work, we design a novel, integrated transmit (TX)/receive (RX) dual-band folded-probe-fed patch (DFPFP) antenna to improve nonlinear radar (NLR) system performance. Designed for down-looking, airborne NLR applications, the DFPFP antenna occupies an improved form factor ( $0.9\lambda \times 0.9\lambda \times 0.1\lambda $ , 1.8 kg) over existing commercial-off-the-shelf (COTS) designs and additionally offers minimal drag in airborne applications due to its low profile. The DFPFP antenna is simulated, fabricated, and tested, and excellent gain (9 dBi) and bandwidth (15%) performance are demonstrated. Iterations of the design from single, standalone TX and RX antennas to the final, integrated design are presented and discussed. The final DFPFP is compared to a pair of COTS antennas that are currently used for NLR system testing. Evaluated in the context of an NLR system, the custom DFPFP antenna significantly outperforms the COTS antennas, with signal-to-noise ratio (SNR) improvements as high as 17 dB, while offering significantly improved size, weight, and power (SWaP) performance.