Joint Beam Steering and Direct Antenna Multi-Modulation using Time-Modulated Arrays

In this paper, we introduce a novel architecture-independent technique for time-modulated arrays (TMAs) that enables simultaneous direct-antenna multi-modulation (DAMM) and beam steering. We validated the approach across a remarkably broad variety of modulation constellations, confirming its ability to implement arbitrary direct-antenna IQ modulation. This flexibility makes the technique highly suitable for Internet of Things (IoT) applications spanning scenarios that demand either robust communication or high spectral efficiency, all on a single energy-efficient, low-cost hardware platform. The proposed method operates within the available TMA bandwidth and achieves precise beam steering without relying on computationally intensive optimization algorithms. Unlike previous studies that evaluate TMAs in isolation, we design and characterize a fully integrated transmitter that combines DAMM and beam steering functionalities. The resulting TMA-based DAMM transmitter employs a reduced hardware architecture, delivering both cost and energy savings ideally matched to resource-constrained, low-latency IoT deployments.