Sub-GHz Multi-Sensor Gateway for Air Quality and Occupancy

Challenge: Single enclosure that monitors air quality (NOx, particulate matter), occupancy (PIR), temperature, humidity, and communicates over sub-GHz for building-wide coverage. Solution: Stacked PCB design: the sensor board sits above the radio/MCU board inside a vented enclosure. The PIR lens pokes through the housing, and the particulate matter sensor has its own airflow channel. A helical antenna provides compact, omnidirectional coverage for wall and ceiling mounting at any orientation. Gas sensor warm-up is staggered to avoid boot current spikes. Results: Building managers get a combined occupancy + air quality view from one device per zone. The sub-GHz link reaches across entire floors through walls, the primary advantage over Wi-Fi or BLE.