Low-Sidelobe Independently Controllable Multi-beamforming Time-Modulated Array with Arbitrary Stepped Waveforms

A low-sidelobe independently controllable multi- beamforming time-modulated array (TMA) with arbitrary stepped waveforms is proposed. Unlike conventional multibeam TMAs with constrained harmonic relationships, independent control of beam directions and amplitude weightings is achieved by assigning harmonic complex coefficients at different operating sidebands. The corresponding time-modulated waveforms are then obtained via inverse Fourier transform and quantized into practical stepped waveforms for implementation using in-phase/quadrature (I/Q) time modulators. Only a few global variables, whose number is independent of the array size, are optimized to improve efficiency while satisfying the sideband level (SBL) and sidelobe level (SLL) requirements. Experimental results from an eight-element prototype with far-field calibration verify independently controllable five-beam radiation with a measured SLL of −19.3 dB and an SBL below −30 dB.