Dynamic Dual-Reflector Antennas for High-Resolution Real-Time SAR Imaging

This paper presents two novel dual-reflector antennas that can generate a synthetic array of phase centers for high frame-rate, high-resolution synthetic aperture radar (SAR) imaging. The antennas consist of a main reflector and a sub-reflector which physically move to shift the phase center of a single transceiver. Digital beamforming is then used to generate a pencil beam with a Half Power Beamwidth (HPBW) less than 0.3° and side-lobe levels below −15 dB for a scanning angle of ±10° in both azimuth and elevation. The estimated array formation time (i.e. inverse of frame-rate) is a fraction of a second. The antennas are designed for a SAR system operating at 240 GHz. Physical optics (PO) is used to model the far-field characteristics. The analytical models are corroborated using the ANSYS HFSS Integral Equation solver.