A Self-Powered Antenna Monitoring System for DAS

This paper presents a self-powered antenna monitoring system (AMS) that harvests energy from a directional coupler on the downlink of a distributed antenna system (DAS). Each ceiling module operates solely from the RF power between the remote unit (RU) and its antenna, requiring no extra power cabling or sensors. A compact PCB integrates a planar monopole, directional coupler, 0.7–1.0 GHz wideband rectifier, energy harvesting power-management unit (PMU) with supercapacitor and Bluetooth Low Energy (BLE) system-on-chip. The coupler samples a controlled fraction of the RU-to-antenna signal and, through the rectifier–PMU chain, provides a stable BLE supply while a small portion is used for RF power monitoring. BLE packets at 2.4 GHz are returned via the coupler isolation port to mobile devices. Measurements show small extra insertion loss, realized gains of 2.56–6.9 dBi over 0.68–6 GHz, and sufficient harvested power for continuous monitoring and rapid DAS fault localization.