TrueRC Singularity 1.2 Ghz - RF Performance

I wanted to do a few quick VSWR measurements on the TrueRC 1.2 Ghz Singularity antenna to confirm that it doesn't get detuned too much when embedded in a foam wing.

Here's the bare antenna:

It's an impressive little antenna. Centered nicely between 1258 and 1280.

And here it is in a VAS Sphinx that was sacrificed in the name of science :)  (Note: there there is only one fiberglass spar in the Sphinx.  I expect a Carbon fiber spar in the near field would detune the antenna, but that will be an experiment for another day)

Impressive! Almost no effect to the VSWR from the foam or the servo near by.

One thing to note (just for the sake of completeness):
VSWR (Voltage Standing Wave Ratio) is a measure of how much energy is reflected back from the antenna.  There are 3 directions that RF energy goes once is leaves the video transmitter.  1: A portion is radiated as EM energy to the environment (we'd love it if 100% went this way).  2: A portion is lost in the feed line or antenna itself due to resistive heating and parasitics (Since we don't have room temp superconductors just yet).  3: A portion is reflected back towards the transmitter if the antenna isn't a perfect impedance match to the transmitter.  The latter is what VSWR is a measure of.  So antenna efficiency can still be negatively impacted bit items in the near field of the antenna even if the VSWR isn't.

So, in the name of science, let's take a look at what's inside:

And just for fun, let see how much things get detuned when we sweep the antenna with the top cover removed:

Quite a bit.  But not too unexpected.  This info might be useful for those wanting to fly 1280 and 1320.

Hope everyone enjoyed the ride!  Leave a comment if you have any questions or suggestions for future experiments.

Thanks!

~pk

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Edit: Oct 29th, 2017

And here are some sweeps with a carbon fiber rod in the near field (~ 0.5 inches away from the edge of the antenna)

Reference measurement: Slot Cut, No CF rod present:

CF rod ends parallel to the edge of the antenna where the feed line enters:

CF rod ends at the midpoint of the antenna:

CF ends 1" past the end of the antenna: