Design and implementation of a continuously steerable antenna array for Synthetic Aperture Radar applications

The design and implementation of a continuously steerable antenna array for Synthetic Aperture Radar applications in the S-band is presented. The system consists of a 4-element Vivaldi antenna array, a 4×4 Butler matrix and four varactor-based phase shifters to achieve continuous beam steering. The stacked antipodal Vivaldi antenna array showed 11dB gain with 30° beamwidth within 2-4GHz. The combination of the Butler matrix and varactor-based phase shifters was able to produce phase differences of up to ±157° between antenna elements within 2-3.25GHz. The integrated setup produced up to ±35° steer allowing a maximum scanning angle of 70° with 30° beamwidth and 11dB gain.