Combined phase-difference and amplitude-comparison technique for Wi-Fi direction-finding with high angular sensitivity and ambiguity mitigation in a wide field of view

• Direction of arrival (DoA) estimation using Channel State Information (CSI) and Received Signal Strength Indicator (RSSI). • Low DoA estimation error of 3.8° in a wide field of view (FoV) of 180° without ambiguities. • Proposed system needs a minimal amount of two passive antennas to cover wide FoV of 180° without ambiguities and using only a single frequency channel. An interferometric antenna system for Wi-Fi direction finding (DF) using only two directive tilted antennas, is proposed in this work. Typically, more than two receiver chains are needed to obtain high angular sensitivity, with a distance between antennas of no more than half wavelength to avoid phase ambiguities. We demonstrate that two directive tilted antennas with a half-power beam width of 30° and separated at a distance of two wavelengths provide high angular sensitivity and mitigate the effect of the phase-difference ambiguities, thanks to the combined use of the phase- and amplitude-comparison techniques. Wi-Fi CSI (Channel State Information) and RSSI (Received Signal Strength Indicator) data are acquired to estimate the direction-of-arrival (DoA) using the proposed joint phase- and amplitude-comparison approach, demonstrating superior DF performance while avoiding complex hardware to perform active scanning or the costly use of a higher number of antennas and synchronized receivers.