A NanoVNA (Nano Vector Network Analyzer) is a small, inexpensive instrument that sweeps a signal across a range of frequencies and measures how a circuit or component responds. It tells you the impedance, resonant frequency, Q factor, and reflection characteristics of whatever you connect to it.
The original NanoVNA is open-source hardware designed by edy555 (Ttrftech). Chinese manufacturing clones are widely available for $25–35.
Which one to get
- NanoVNA-H: The standard version. 50 kHz to 900 MHz. Small screen. ~$25.
- NanoVNA-H4: Larger 4-inch screen, same frequency range. Easier to read. ~$35.
- NanoVNA-V2 (S-A-A-2): Extended range to 3 GHz. Overkill for most experiments but nice to have. ~$60.
Any of these works for the Open Energy experiments, which typically measure in the kHz to low MHz range.
What it measures
- S11 (Return Loss): How much signal reflects back from the device under test. A dip in S11 = a resonance.
- |Z| (Impedance magnitude): How much the circuit opposes current at each frequency.
- Phase: Whether the circuit is behaving more like an inductor or a capacitor at each frequency.
- SWR (Standing Wave Ratio): Related to S11 — useful for antenna work.
- Q factor: Many firmware versions calculate this automatically from the resonance peak.
How to use it for coil experiments
- Connect your coil to the CH0 port via an SMA-to-clip cable
- Set the sweep range (e.g., 100 kHz to 30 MHz)
- Calibrate (open, short, load — the NanoVNA kit usually includes calibration standards)
- Look for the impedance peak — that's the self-resonant frequency
- Read the Q factor and impedance magnitude at the peak
- Save or photograph the screen
The first experiment tutorial walks through this step by step.