Nematic liquid crystal (NLC) technology-based optical systems for controlling phased array antennas are presented. These systems can provide low cost, high quality (> 6 bit), phase-based antenna control for very large phased arrays (e.g., 5000 elements). An experiment demonstrating NLC-based antenna phase control is performed, with 0-3pi phase shift measured for a 60-MHz carrier. A novel time-multiplexed radar beam scanning approach is introduced to counter the slow response of the NLC's, allowing fast 200 beams/s antenna scanning rates.Nematic liquid crystal (NLC) technology-based optical systems for controlling phased array antennas are presented. These systems can provide low cost, high quality (> 6 bit), phase-based antenna control for very large phased arrays (e.g., 5000 elements). An experiment demonstrating NLC-based antenna phase control is performed, with 0-3pi phase shift measured for a 60-MHz carrier. A novel time-multiplexed radar beam scanning approach is introduced to counter the slow response of the NLC's, allowing fast 200 beams/s antenna scanning rates.