On 8/13/21 8:06 AM, Syd via groups.io wrote:
I saw a video about the dangers of using the nanoVNA by connecting to the antenna coax: static buildup on the coax. So I guess one way around this is to measure right at the antenna. The nano is portable. But that still leaves the coax so I suppose that I should short out the coax before measuring it. Any other measures/precautions about measuring out doors antennas?
syd/wt1v
Static will build up on the antenna, not just the coax. Or even the stuff sitting on the bench.? The ESD sensitivity varies substantially among the various small VNAs. Some have resistor bridges/pads right on the inputs.? Others have MMIC switches. The latter are more sensitive.
The other thing to worry about is nearby transmitters inducing sufficient power into your antenna to cause problems.
I suppose, one could check for any of these by measuring the AC voltage across a 50 ohm load hooked up to the UUT, with a simple (cheap, sacrificeable) diode probe. A 1N4001 and 0.01 uF would probably work, since you're looking for "volts" not "microvolts". A $10 DMM, diode, etc.
