The QuadRF is a handheld phased-array radio built around a Raspberry Pi 5 and an FPGA board with picosecond-level timing, capable of beamforming and advanced signal processing across the 4.9-6 GHz C-band. Created by Martin McCormick, a former SpaceX engineer who worked on the original Starlink Dishy terminal, the device can visualize WiFi networks through walls and track drones in flight — demonstrated by detecting a DJI Mini Pro 4 at distance. A basic kit is available for $499 on Crowd Supply, with a Mobile Expansion Pack adding battery power and a phone mount for field use.

The architectural breakthrough lies in streaming I/Q (In-phase/Quadrature) data over the Pi 5's MIPI camera and display FFC connectors at over 5 Gbps through the RP1 chip. This approach delivers low-latency, full-duplex transfer with zero sample loss at hundreds of MSPS, avoids USB complexity, and leaves the PCIe lane free for storage or networking. The design also supports daisy-chaining multiple QuadRF modules, each calculating its own phase shift, enabling scalable array configurations.

Testing revealed a functional but rough browser-based VNC interface launching GNU Radio, SDR tools, and a custom AR visualizer that renders RF frequencies as colored blobs. Gain control lacks AGC and feels clunky during mobile use. The 3D-printed enclosure will shift to injection molding as the crowdfunding campaign exceeds expectations.

QuadRF proves that sophisticated phased-array capabilities — once limited to military or satellite systems — can now fit in a handheld open-source platform. The MIPI-based I/Q streaming architecture could influence broader SDR hardware design, while the drone-tracking demo underscores growing privacy implications for consumer RF emissions.