Abstract: Analog time delay units (TDUs) are usually used for wideband phased array beamforming, but quantization error and high cost restrict their applications. This paper analyses first the fact that TDUs quantization error will reduce signal power and range resolution, and then a new wideband digital beamforming method using subarrays and linear frequency modulation(LFM) signal is proposed. The algorithm, which implements the stretch processing and narrowband filtering technique, achieves digital beamforming by weighting inter-subarrays in the time domain. Lowpass filtering limits the bandwidth of the signal prior to digitization and signal processing, reducing the required speed of subsequent digitization and the computing burden. Finally, computer simulatioins demonstrate that digital beamforming eliminates the effect of quantization error and has better performance than the analog TDUs method.

Key words: wideband phased array, digital beamforming, quantization error, stretch processing