I have a whole load of rubber duck antennas that I'm checking so see at
what range they should work best.
Ken,
the behavior of rubber duckies depends significantly on the radio they are attached to. So, to get reasonably accurate results when measuring them with the nanoVNA, I suggest that you build a metal bracket about the size of a typical HT, covered with some insulation to mimmick the plastic body of an HT, mount the nanoVNA in that bracket, its measuring port bonded to the bracket, and then hold that contraption in your hand like you would hold an HT, while making the measurements.
You could even use a plastic box the size of an HT, covered with aluminium foil on the inside, properly bonded to the nanoVNA's port.
Of course you need to run the nanoVNA without an USB cable connected.
You will see that depending on how you grab that test contraption, the measured values will shift somewhat. If you mount the antenna directly to the nanoVNA, they will shift more, since the nanoVNA is a lot smaller than an HT, at least the 2.8" screen version. I haven't compared the size of the H4 version to that of an HT. It should be closer, but maybe not close enough.
Perhaps someone else can comment on how accurate the measurements come out when mounting a rubber duckie directly on an H4?
Manfred
