Nano VNA V2 S-A-A-2 hardware overview

NanoVNA V2 (S-A-A-2) is a low cost 3GHz T/R vector network analyzer developed by HCXQS in collaboration with OwOComm. The V2 hardware is a new from-scratch design and is not based on the original NanoVNA by edy555. Compared to the original NanoVNA, V2 does not use harmonics for measurements and achieves higher dynamic range.

NanoVNA v2 (Vector Network Analyzer) is a device that facilitates the analysis of complex signals. During measurements, the device measures both the amplitude and phase of the signal. A VNA can help make sure the antenna is properly tuned to the correct frequency. Compared to the standard SWR meter, the VNA also provides phase information.

The device has a 2.8 ”display and a touch panel (unfortunately resistive). You can conveniently configure the device and read the indications of the measurement. The menu map facilitates the navigation of the user interface.

NanoVNA v2 S-A-A-2 for firmware version 20200501.

We go to the set menu by touching the screen anywhere or by pressing the central button (marked on the PCB as S3). The menu can be navigated by the keys (marked on the board as S1 and S4) or by using the touch panel of course. Before beginning work, it is worth calibrating the touch panel and check behaviour.

Hardware

The construction measures 90 x 54 x 24 mm and weighs about 135 g. There is a battery under the mentioned screen. The analyzer is powered by a battery with a capacity of 2000mAh. The battery charging current is 1.2A. The maximum power consumption of the device is about 0.4A.

VNA construction inside.

In addition, the device has a micro-B USB connector for powering the device, charging the battery and communication with a computer via a serial port. The battery charge indicator consists of four red LEDs. This indicator is located under the power switch.

NanoVNA has two SMA ports. One of them marked as S11 is the reflectivity. In turn, the second – S21 is the transmittance coefficient of the tested object.

Moreover, the theoretical bandwidth for the NanoVNA v2 device is in the range from 50kHz to 3GHz. This makes it possible to work with the majority of generally available radio bands. For example, we can tune the antenna to work in the ISM radio band.

The device requires calibration after changing the operating frequency range. The narrower the frequency range, the more accurate the measurements are. Keep this in mind.

Hardware architecture

The S-A-A-2 is a highly cost optimized design that aims to achieve the best possible RF performance within a tight BOM budget.

Two ADF4350 RF synthesizers, plus one Si5351, provide the stimulus and LO signals. The Si5351 covers frequencies up to 140MHz, and the rest are covered by the ADF4350s. The main microcontroller is STM32F303.

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