My assumption here is that to correctly test, I should be using the same antenna on a pair of devices, with no other devices playing part of that mesh (i.e. cheating by providing a better hop). This is to make sure I get a truer reflection of both the transmitting and receiving effectiveness.
Is this a correct or good approach, or is the a simpler/better one?
VNA gives you only S parameters so you know how your antenna looks electrically. What is its impedance and reflection but you know nothing about efficiency and antenna gain.
If you want measure antenna you can use VNA. But if you want know how your antenna is effective you need at least field test. Or better test in chamber on rotator and proper software with generator and reciever / spectral analyzator.
Go to Google and search for the best Antennas that humans have built in the history of Radio Communication
There are many photos or models of antennas that must not be invented but built for personal use and with the desired frequencies.
You just need to have interest and creativity
Edit: However the VNA gives you a clear idea of the quality of the antenna. You don’t have to use thousands and thousands dollar equipment to know if the antenna is actually good or not.
Communication is made by words
However, if someone here wants to build antennas they have to do a little research to understand their needs and what they need.
Words could not help so much but experience and manual skills built over time.
However someone above seems to have problems measuring the effectiveness of the antenna with the NanoVNA, I remind you that the NanoVNA measures both the swr but also the decibels of the antenna. No nasa laboratories are needed to test them.
A deep hole in the spectrum of the NanoVNA means that the radiated power is almost all translated into radiation with no return back into the radio amplifier, that is the effectiveness of the antenna.
However, if we want to give the narrow or wide projection, the shapes of the antenna and the elements that can be added come into play.
Your NanoVNA and Google is the best friend in all the situations
“A deep hole in the spectrum of the NanoVNA means that the radiated power is almost all translated into radiation with no return back into the radio amplifier, that is the effectiveness of the antenna.”
You ar not right. Check my nearly perfect antenna here.
If you put a 50 ohm Dummy Load you can have an even better antenna than that resistor you put in!
In fact I’ll show you a perfect antenna too “In reality it’s not perfect at all” it sucks “but measured on purpose to make it look so”.
I think you have a different concept of how you see the VNA working and how the Smith chart works that I totally disagree.
This however is my opinion what I think, since I have a lot of experience, but it does not mean that I am right or not. Maybe you’re right, maybe I’m wrong who knows
It is an honour to meet you, your videos taught me so much about LORA and all things RF, Thanks for telling all makers to get a VNA even if it is a Nano, Yet to get my T beams, they should be here by next week while I wait, practising how to make 433mhz antennas of varying types and figuring out how to tune them, So far I have made 1 433mhz Folded end Dipole, please look at my readings and tell me what you think. Please see Finally got me a VNA (noobie)
Best way with minimal equipment is to use one good antenna on one end and either find a second known good antenna or evaluate an antenna against the known good which will give you a comparison against your “reference”. Subsequent antennas will be either better or worse, or the same, as your reference. If you are testing a lot of antennas you can eventually find the highest performer and then start using it as your new reference.
You will also need some kind of metric to use to evaluate. BER is only good if you are near the fringe of its range. Because you won’t see anything better than 0 BER. Someone mentioned RSSI but that can fluctuate a lot so it would take some really long term averaging in order to get meaningful results.
Since antennas are reciprocal, you could get a rough gauge of an antennas efficiency operating at close range by using RSSI. Get it up out of the noise and just measure the TX power of the “known good” with the DUT and do the whole reference eval I described above. This will give you a relative measure of the antennas gain. Best scenario is you can get a hold of two antennas that have been characterized to calibrate the link. Then everything is relative to it.