Build a desktop antenna-measurement rig out of four ESP32-C3 boards and a motorised turntable. Beambench rotates the antenna under test, measures how strongly a radio signal arrives at each angle, and plots the result live in your browser as a polar diagram — so you can actually see in which directions an antenna sends or receives best.
Hardware, firmware, and the PC app are all open source.
⚠️ Disclaimer — proof of conceptThis entire project was written with Claude Code and has not yet undergone any proper code review. It exists purely as a proof of concept for demo purposes. Do not rely on it for anything that matters — expect rough edges, missing validation, and untested corners.
The antenna under test sits on a motorised turntable. A TX board sends short radio packets; an RX board measures the signal strength of those packets. A Turntable board rotates the motor through 360° in small steps, and a Bridge board hooks the whole thing up to the PC over USB. The browser UI plots the result as it comes in — angle = direction, distance from the centre = signal strength.
┌──────────────────────────┐
│ PC — Browser UI │
└─────────────┬────────────┘
│ USB-serial
┌─────────────┴────────────┐
│ ESP32-C3 — Bridge │
└─────────────┬────────────┘
│
│ ESP-NOW (2.4 GHz)
│
┌────────────────────────┼────────────────────────┐
│ │ │
┌────────┴─────────┐ ┌─────────┴────────┐ ┌──────────┴────────┐
│ ESP32-C3 — TX │ │ ESP32-C3 — RX │ │ ESP32-C3 — │
│ on turntable, │ │ fixed position, │ │ Turntable — │
│ antenna under │ │ reference ant., │ │ drives the │
│ test, battery │ │ measures signal │ │ stepper motor │
└──────────────────┘ └──────────────────┘ └───────────────────┘
│ ▲
│ radio signal under │
└────── measurement ─────┘
software/
├── protocol/ Shared no_std message types (postcard + serde)
├── firmware/ Unified ESP32-C3 firmware; role chosen via Cargo feature
└── pc/ PC app — Axum backend + Svelte frontend with Plotly polar plot
The firmware is one crate with feature flags (role-bridge, role-tx, role-rx, role-turntable). Every board flashes the same code; only the feature changes.
- PC ↔ Bridge: COBS-framed postcard over USB-serial (or TCP for the simulator)
- Bridge ↔ TX/RX/Turntable: postcard-serialised messages over ESP-NOW
Requires Rust nightly and probe-rs for flashing.
# Try it with no hardware: bridge simulator + dev server
just sim # in one shell
cd software/pc && just dev # in another → http://localhost:5173For real hardware, flash one role per board:
cd software/firmware
cargo run --release --no-default-features --features role-bridge
cargo run --release --no-default-features --features role-tx
cargo run --release --no-default-features --features role-rx
cargo run --release --no-default-features --features role-turntableOnce the boards are paired, follow-up firmware updates can be pushed wirelessly with just ota-<role>.
Four ESP32-C3-DevKit-RUST-1 boards plus a stepper-motor driver. Default driver is the MKS SERVO42D (step/dir); a UART variant (SERVO42C) is also supported.
Step/Dir wiring (default):
| ESP32-C3 | SERVO42D | Function |
|---|---|---|
| 3.3 V | COM | Common anode |
| GPIO4 | STP | Step pulse |
| GPIO5 | DIR | Direction |
| GPIO6 | EN | Enable (active low) |
| GND | GND | Ground |
| — | V+ | 12–24 V supply |
Motor: 200 full steps × 16 microsteps = 3200 steps/revolution (≈ 0.1125°/step). The motor-to-turntable gear ratio is configurable in the UI (default 1:3).
just test # all host-side tests
cd software/pc && cargo test --features sim # PC unit + integration suiteThe integration suite spins up an in-process bridge simulator that generates synthetic cardioid RSSI data — useful for testing the whole pipeline without flashing anything.
Released under the MIT License. © 2026 Systemscape GmbH.