Category: Transmission lines

The NanoVNA is a new low cost community developed VNA with assembled units coming out of China for <$50.

This article documents some tests using a small ferrite cored test inductor that provides a similar impedance to that of a common mode choke suited to HF antenna feed lines.

The nanoVNA-H has firmware NanoVNA-Q-0.4.3-20f33ba.dfu installed. The nanoVNA appears to be a nanoVNA-H v3.3 but it is hard to be sure, it is from China, the land of copyists and fraud. Indeed the nanovna-Q author asserts that genuine nanoVNA-H have a green overlay whereas mine is blue. Uncertainty is part of the territory!

A small fixture was OSL calibrated and impedance measured by reflection (ie s11).

The results broadly reconcile with previous measurements of the inductor, but the jitter is worth of examination.

Above is a chart showing the measured impedance components, we might expect a reasonably smooth curve for each. It has a lot of jitter on it, and you might excuse that as a result of applying the instrument and method to such a high impedance… but for two things: Continue reading nanoVNA-H – a ferrite cored test inductor – drilling down on a glitch – the fix

The NanoVNA is a new low cost community developed VNA with assembled units coming out of China for <$50.

I have been evaluating one for common tasks around a ham station and noticed a persistent glitch around 7.5MHz in scenarios where |s21| is high.

The nanoVNA-H has firmware NanoVNA-Q-0.4.3-20f33ba.dfu installed. The nanoVNA appears to be a nanoVNA-H v3.3 but it is hard to be sure, it is from China, the land of copyists and fraud. Indeed the nanovna-Q author asserts that genuine nanoVNA-H have a green overlay whereas mine is blue. Uncertainty is part of the territory!

Above is an example where a ferrite cored inductor similar to an antenna common mode choke is measured, and the underlying curves should be smooth with some random measurement noise. The glitch around 7.5MHz is persistent and much larger than the random noise, so I have investigated further. Continue reading nanoVNA-H – a ferrite cored test inductor – drilling down on a glitch

The NanoVNA is a new low cost community developed VNA with assembled units coming out of China for <$50.

This article documents a task to perform a VSWR sweep of a VHF antenna stand alone, and to capture the data and screen image for download to a computer.

The nanoVNA-H has firmware NanoVNA-Q-0.4.3-20f33ba.dfu installed.

The instrument was OSL calibrated for reflection at Port 1 (Ch0 is nanoVNA speak, convention means little) for 100-500MHz.

A sweep was then performed from 143-149MHz, forcing some interpolation of the calibration data.

The nanoVNA was configured for VSWR and Smith chart displays, much as you would to use it stand alone.

The sweep was then “Paused”, and the nanoVNA carried to the computer and plugged into the USB. The power must not be disturbed, the controls must not be altered, the captured data is really just what is frozen on the paused display.

Note that if the thing is unplugged from the USB the nanoVNA resets and the data is lost, so plug it in properly just once.

I then connected to it using using nanoVNA MOD v3 and captured the screen, clicked get data once, and saved the .s1p file.

Above is the cropped screen capture. Continue reading nanoVNA-H – standalone VHF antenna VSWR sweep

The NanoVNA is a new low cost community developed VNA with assembled units coming out of China for <$50.

This article documents a task to perform a VSWR sweep of a UHF mobile antenna.

The nanoVNA-H has firmware NanoVNA-H_20191018.dfu installed.

The instrument was OSL calibrated for reflection at Port 1 (Ch0 is nanoVNA speak, convention means little) for 100-500MHz.

A sweep was then performed from 400-470MHz, forcing some interpolation of the calibration data.

The nanoVNA was configured for VSWR and Smith chart displays, much as you would to use it stand alone, but I did have it attached to the computer to capure the display (it seems it cannot be saved for later playback).

Above, the captured display. The results are pretty much as expected, no surprises there. Continue reading nanoVNA-H – mobile UHF antenna VSWR sweep

The NanoVNA is a new low cost community developed VNA with assembled units coming out of China for <$50.

This article documents some tests using a small ferrite cored test inductor that provides a similar impedance to that of a common mode choke suited to HF antenna feed lines.

The nanoVNA-H has firmware NanoVNA-H_20191018.dfu installed.

A small fixture was OSL calibrated and impedance measured by reflection (ie s11).

The results broadly reconcile with previous measurements of the inductor, but the jitter is worth of examination.

Above is a chart from nanovna-saver showing the measured impedance components, we might expect a reasonably smooth curve for each. It has a lot of jitter on it, and you might excuse that as a result of applying the instrument and method to such a high impedance… but for two things: Continue reading nanoVNA-H – a ferrite cored test inductor

The NanoVNA is a new low cost community developed VNA with assembled units coming out of China for <$50.

It is a semi open source project, some information is published in open access places like unrestricted github and currently unrestricted acccess messages in a io.groups forum, but the wiki and files collection of that forum is by membership only and so is not publicly available.

After reviewing a lot of public information, I chose to try  purchase an Nanovna-H. There were trials along the way in that Hugen79’s preferred supplier on Alibaba could not accept my suburb in the address, so I searched eBay, Amazon and Aliexpress for items that appears to be a Nanovna-H. On the day, eBay and Amazon had no listings, but there were some on Aliexpress.

In this case, though the seller lied about material things, it does appear that I received a ‘genuine’ nanoVNA-H, and one of very recent manufacture as it had firmware dated two days after I placed the order.

The device was charged and needed only an hour to reach full charge, it was about 75% charged. No grief with the battery manager stuck in shutdown (yet) as some users report.

Above, the nanoVNA-H as received. Continue reading nanoVNA-H – first experience

The NanoVNA is a new low cost community developed VNA with assembled units coming out of China for <$50.

I purchased what appears to be a ‘genuine’ nanoVNA-H and it has firmware NanoVNA-H_20191018.dfu installed. During checkout of the delivered device, an issue became evident, an issue worth describing in its own article.

Glitches on the displayed data are occasional, but hardly rare, and are a concern.

The nanoVNA was OSL calibrated (is for reflection only) from 1 to 500MHz and the cal save in C4.

On repeated scans of the SC used for the cal, there are obvious occasional glitches evident on various PC clients.

Above is nanovnasharp v1.03. An expanded scale shows the observation, an occasional single measurement, always with a downwards glitch  of |S11|dB of variable magnitude, but usually less than a couple of dB. Continue reading nanoVNA-H – occasional glitches in measured data