If you are on Windows, you need the correct driver.
There is a specific satisfaction in turning a $50 piece of test equipment into a lab-grade instrument. The NanoVNA S-A-A-2 (often based on the LWVVM design) is a marvel of modern RF engineering, but its biggest limitation isn't its dynamic range or frequency coverage—it’s the interface.
Hunting for markers with a stylus on a 4-inch resistive touchscreen is an exercise in patience. This is where NanoVNA-QT enters the chat, transforming the S-A-A-2 from a portable "swiss army knife" into a serious desktop vector network analyzer.
Setup & Connection Connecting the S-A-A-2 to NanoVNA-Qt is generally plug-and-play.
Note: The S-A-A-2 uses a slightly different USB-Serial chip than the original "H" version. Sometimes you need to ensure your USB drivers are up to date, but once connected, the serial link is stable. nanovna-qt pc software with the s-a-a-2
Interface Layout The layout is classic "engineer's GUI"—functional, but not pretty.
The NanoVNA family of vector network analyzers put powerful RF measurement tools into the hands of makers, ham radio operators, and RF tinkerers. Paired with NanoVNA‑Qt — a modern, actively developed desktop application — and an S‑A‑A‑2 antenna analyser adapter (SAA2) or similarly named serial adapter used to interface older NanoVNA hardware, you get a streamlined workflow for calibration, sweeping, and saving measurements for analysis and antenna tuning. This post walks through setup, practical tips, and common workflows so you can get accurate S11/SWR and impedance plots with minimal fuss.
Even with great software, problems occur. Here is how to solve them with the nanoVNA-qt and S-A-A-2 combo.
Issue: "Failed to open device" or "Permission denied." If you are on Windows, you need the correct driver
Issue: Sweeps are extremely slow (2 seconds per sweep).
Issue: The trace looks like a "Shaggy Carpet" (noisy).
The S-A-A-2 screen only shows one Smith chart scale. In nanoVNA-qt, hold Ctrl and drag a box on the Smith chart to zoom into the 0.9 to 1.1 VSWR region. This allows you to perfectly match a high-gain yagi antenna.
| Feature | nanovna-qt + SAA-2 | NanoVNA-Saver + SAA-2 | |--------|-------------------|------------------------| | Real-time sweep | Excellent | Good (slightly slower) | | 3 GHz support | Yes | Yes | | Touchstone export | Yes | Yes | | TDR | Basic | Better (with impulse response) | | UI polish | Minimal | More polished | | Cross-platform | Yes (Qt) | Python (requires dependencies) | Note: The S-A-A-2 uses a slightly different USB-Serial
Verdict: Use nanovna-qt for quick, low-latency sweeps. Use NanoVNA-Saver for advanced post-processing.
First, a quick refresher. The S-A-A-2 is a 2-port Vector Network Analyzer covering 50 kHz to 3 GHz. Its key upgrades over older models include:
However, navigating deep Smith charts, saving screenshots, or logging sweep data on that 4-inch display is tedious. This is where NanoVNA-QT steps in.