In this work, a set of custom folded-probe-fed patch (FPFP) antennas are designed to improve the performance of a nonlinear radar (NLR) system. To improve system performance, the custom antennas are designed to have high gain, relatively narrow bandwidth, good linearity, and good size, weight, and power (SWaP) performance. Two FPFP antennas are built and tested, one each for transmit and receive. The FPFP antennas are compared to a pair of commercial off-the-shelf (COTS) antennas that are currently used for NLR system testing. Evaluated in the context of a NLR system, the custom FPFP antennas significantly outperform the COTS antennas, with signal-to-noise ratio (SNR) improvements as high as 20 dB. Next, in order to further improve the SWaP performance, the two FPFP antennas are combined into a single, integrated, dual-band folded-probe-fed patch (DFPFP). The DFPFP antenna is fabricated and tested, and its performance is evaluated in the NLR system. Measurements show that the DFPFP antenna provides performance similar to the two separate FPFP antennas, while offering significantly improved SWaP performance.