Demonstration of Fast OTA Chirp-Based Beam Training Using Analog TTD Array with Millimeter Wave Testbed for Applications in Radar Systems

Radar and communication systems operating at millimeter wave frequencies require fast beam training solutions for precise localization. True-Time-Delay (TTD) arrays can implement rainbow beams with frequency-to-angle mapping, enabling a single-shot scan across all angles. In this work, we propose the design of a TTD codebook to facilitate fast beam training using the received chirp signals. The configuration of TTD delays and phases is specified, and a time-domain signal processing algorithm is proposed to estimate the angle-of-arrival (AoA) from instantaneous received power measurements. We demonstrate chirp beam training experiments over-the-air using a 28 GHz TTD testbed with a 4×1 receiver antenna array, along with discussions on the time-synchronization and phase calibration needed to estimate the AoA based on real testbed measurements.