Wideband Beamforming using Digital Phase Only Compensation in Digital Array Radars

Abstract

Phased array Radars use Wideband waveforms for high range resolution and imaging purpose. The classic active phased array radar with a transmit/receive (T/R) module with attenuator and phase shifter of its antenna elements works well for narrowband signals. For large phased arrays with wide band width, to seer the beams in off-broadside true time delay (TTD) devices should be used to avoid beam squinting or bandwidth dispersion effects. The TTD devices require temperature stabilization and provides only quantized delays. True Time delay digital beamforming using fractional delay filters eliminates drawbacks of analog TTD. But it requires high speed devices and interfaces at each element. In this paper a new approach is proposed for wideband digital beamforming (WDBF) for digital array radars with element level digitization capability. This novel approach uses digital phase compensation during transmit waveform generation. During reception stretch processing is used to limit the receive processing bandwidth. This method works with very less computational and does not require fractional delay digital filters. Numerical simulation results are provided to demonstrate the performance of the proposed method.