Low-Sidelobe Single-Sideband Time-Modulated Phased Array Using Stepped Waveforms With Different Amplitudes

Single-sideband time-modulated phased arrays (STMPAs) can suppress undesired sidebands and achieve convenient beam scanning without repeated time-consuming optimization, as compared to conventional time-modulated arrays (TMAs). However, most of STMPAs are limited to phase-only weighting arrays because the conventional method for achieving amplitude weighting significantly reduces the suppression of undesired sidebands. In order to simultaneously achieve convenient beam scanning, low sideband level (SBL), and low sidelobe level (SLL), a general amplitude weighting method based on stepped time-modulated waveforms with different amplitudes in STMPA is proposed in this article. By selecting an appropriate number of steps, time-modulated waveforms can achieve various amplitude weighting values with a large dynamic range. This enables continuous and precise control of the amplitude weighting for each element. By utilizing this method, it is convenient to design time-modulated waveforms for each antenna element independently to suppress undesired sidebands, which avoids repeated time-consuming optimization during beam scanning. To verify the proposed method, an eight-element low-sidelobe STMPA was fabricated and tested, with a measured SLL of -3.53 dB and a measured SBL of -33.34 dB. Additionally, a calibration method for STMPAs is presented to ensure accurate amplitude and phase weighting in practice.