The Quad RF project delivers a phase‑coherent four‑channel SDR that finally gives hobbyists access to radio direction finding. It pairs a custom RF board, housing four 4.9‑6 GHz patch antennas with switchable polarization, to a Raspberry Pi 5 for extra processing. An on‑board Lattice ECP5 FPGA links to the Pi via two MIPI cables, enabling fast camera‑display data paths and Ethernet or Wi‑Fi output, and supports firmware upgrades via GitHub.

Software support includes GNU Radio compatibility and several native tools. The standout is an RF camera that sweeps the full band at 30 fps, computes arrival angles and renders a spatial plot, and logs results for analysis. Overlaid on a video feed it visualizes live emitters; the creators demonstrated tracking a flying drone and separating its two transmitters.

Because each board can interlock into a lattice, developers can scale to larger phased arrays for research or signal‑intelligence work. The ability to both receive and transmit opens doors for experimental radar or mesh networking, though users must heed export‑control and weapons‑use regulations, while remaining open‑source under MIT license. Quad RF therefore lowers the barrier to sophisticated RF imaging for the maker community.