A Self-Powered Antenna Monitoring System for DAS

This paper presents a self-powered antenna monitoring system (AMS) that energy harvesting 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. A compact PCB integrates a planar monopole antenna, coupler, 0.7–1.0 GHz wideband rectifier, energy harvesting power-management unit (PMU) and Bluetooth Low Energy (BLE) SoC. The coupled RF power is converted by the rectifier-PMU chain to supply BLE, while a small fraction is used for RF power monitoring. BLE packets at 2.4 GHz are routed through the coupler isolation port toward the RU, then radiated by an added 2.4-GHz coupler and antenna for reception by a nearby phone or PC. Measurements confirm low added insertion loss, 2.56–6.9 dBi gain from 0.68–6 GHz, and sufficient harvested power for continuous monitoring and rapid fault localization.