Multi-Harmonic Amplitude Analysis of Space-Time-Coding Direct Antenna Modulation for Target Angle Estimation and Vital Sign Detection

This paper presents a new kind of space-time-coding (STC)-enabled direction-finding approach for human target localization in smart healthcare environments. The method overcomes the limitations of angular detection coverage constrained by monotonic linear regions by utilizing multi-harmonic amplitude analysis of STC harmonics. Angular information is estimated by selecting and averaging the nearest angle data points across harmonic power-level differences and angle mapping sets, leveraging the STC harmonic beam steering features. Experimental validation on a direct antenna modulation (DAM)-enabled STC array confirms the effectiveness of the proposed angle estimation method and demonstrates its ability to extract vital signs from the respective STC harmonics.