Two new toys for testing antennas

[Brian.D]

I recently picked up two devices (not really toys) for testing and viewing what my antenna(s) see. Both were less than $60 and I think are a must on a sailboat.

NanoVNA
The NanoVNA is a small, compact Vector Network Analyzer. This tool has many functions, but the one(s) most notable for the sailor is the SWR and TDR functions. It will also tell you the impedance, the attenuation, and the velocity factor of the cable.

The SWR function will tell you if your VHF antenna is tuned correctly. Tuned meaning that Standing Wave Curve(SWR) is lowest at the Marine VHF Frequency Range. Low SWR is an indication that one is getting the most power available at the antenna to be radiated. The TDR function will tell you the length of your cable and if there are any problems with the cable, where along the length of he cable the problem lies. Two major problems are shorts and opens. TDR will tell you which.

The best part of the NanoVNA vs an SWR meter is the lack of RF power needed for testing. With an SWR meter, one must key the radio on a specific frequency to determine the SWR. With the NanoVNA, it generates an unmodulated sweeping signal across a specific range of frequencies which will not interfere with any communications in progress. The power output is about 3dBm (.002 watts). The end result will be a curve telling you where the antenna is currently tuned. One will still need to climb the mast to make adjustments unless one's mast has been unstepped.

TinySA
The TinySA is a miniature Spectrum Analyzer. Miniature in size, not in function. This tool will tell you what your antenna is hearing. This tool is not as important as the NanoVNA, but it you are having receive issues, this tool will tell you. How one uses it depends on what one wants to accomplish. If one has a handheld radio available, just attach the TinySA to the boat's VHF antenna cable and key the handheld radio. One should see a spike showing the power level and the frequency. If the spike is not present (assuming all settings are correct) then it can be assumed that the antenna is not working. This can also be used with the AIS antenna. One should note that this type of testing is intrusive, meaning, it will interfere with any communications in progress. Listening before keying.

TinySA also has a RF generator that is adjustable. One can connect it to the VHF antenna and test for output power without the fear of damaging your VHF radio. Again, using the handheld will help in determining if your are actually transmitting a signal or not.

Both tools are inexpensive and easy to use out of the box. There are multiple videos showing the uses of both tools. Too numerous to mention here, just do a Youtube search. Watch the videos and see if you might be able to use one, or both, of these tools.

Obviously one needs to be careful when ordering. Our friends in China are very busy cloning these tools and the clones do not work correctly. For the TinySA, go to the TinySA.org site and look for the recommended sellers. Some of the sellers also sell the NanoVNA.

Hope you find this info useful. Again, having useful tools on a boat when it comes to your communications equipment means keeping that equipment in proper working order.

[smac999]

I have used professional swr anilizers before but they are $$$$

Would love to have one.

Curious how this one stands up

[smac999]

Googling the nanovna there are many different company’s selling the same thing.... even on amazon. Same product
Nane by different company’s for different prices ...

[Paul L]

I bought a NanoVna a while back. Played with it a bit. Enough so it gave me SWR results that felt good enough. Pretty powerful for $60. The construction is not very robust, but still a good toy to have.

[Brian.D]

I got my NanoVNA from Amazon and my TinySA from R&L Electronics.

[Jammer]

I've had a NanoVNA for over a year. It's a great product for the money.


The hardware and software are both open source. The original developer released construction details and files to encourage inexpensive manufacturers to come forward, which they have.

[Cadence]

Brian D,
An excellent writeup.
Thanks!

[waterman46]

I got one of the little VNA's a couple months ago. Having used industrial VNA's (HP) for many years, ones that cost multiples of $10,000, I am simply beyond amazed what they have done now with the technology. Seems accurate enough for most anything we would have needed back in the day.

Thanks to the OP for pointing out the uses of these on our boats.

[iota27]

Brian D. Many thanks for the very useful info.
Jack, W1IU

[jsharp]

This excellent. As kind of a tech type myself, I will grab both of these.

I remember more than 30 years ago hiring someone to troubleshoot and fix an RF issue. The guy might as well have been a witch doctor with all that came spouting out of this mouth while he begrudgingly worked on my issue. The stuff he had in his van looked like something out of ghostbusters, with just about every frequency of antenna on the van as well. Analog as it was, it was also the best that we had back then. Now we can have our own about the size of Spock's tricorder... Joe

[Bawlmer]

Wow. Things have really changed. I remember they used to cost a kings ransom and having to grovel to my boss to get one for the shop. I'm definitely getting one. For 60 bucks, how can you go wrong.

[Brian.D]

Here are the user groups that can help if you questions/issues.

TinySA - https://groups.io/g/tinysa
NanoVNA - https://groups.io/g/nanovna-users

Also, for the NanoVNA they come in two sizes: standard NanoVNA-H is 2.8", and larger NanoVNA-H4 is 4". The firmware for both H and H4 can be the standard VNA firmware, or the Antenna Analysis (AA) firmware. I use the AA firmware on my -H model.

[Catboat Willy]

Thank you for a great recommendation and great write up. I've been wondering just what to get a view of the SWR on the on board low band rig. Looks a lot better than the MFJ device.
de.... W2CWL/MM

[Jerry Woodward]

I recently installed a Vesper XB8000 AIS, the Vesper splitter, and the Vesper antenna recommended to be the best for both AIS and VHF. However, I used the existing coax cable in the mast. Everything works fine, but I have no idea how much signal I am losing in the coax. Will one of these gadgets tell me how much of my signal I'm losing in my coax?

[smac999]

if something was wrong you'd get a bad SWR. but it it's good 50ohm cable just small and long. the only way to know the loss would be to measure power output at the bottom and at the top of mast and calculate the difference... with a power meter. which this is not