Re: Connect Antenna Trap to NanoVNA


Jerry Gaffke
 

Also, after thinking about this a little bit, the resonant frequency of the
trap likely stays pretty much put.
However, the trap would significantly affect the antenna resonant frequencies for which the trap is not resonant.

Which is to say, you'd best listen to somebody else!

Jerry, KE7ER

On Tue, Sep 29, 2020 at 10:44 AM, Jerry Gaffke wrote:

Correction to an obvious error:
Parallel tuned is a high impedance at resonance.
Jerry, KE7ER
Hide quoted text ( #quoted-173058290 )

On Tue, Sep 29, 2020 at 08:36 AM, Jerry Gaffke wrote:



I would probably test a parallel tuned trap as a single port, with the far
end
of the trap grounded.
Should see the impedance head towards zero at the resonant frequency.
But could also be done as a 2 port measurement, loss approaching zero at
the
resonant frequency.

You will find that the resonant frequency will change when the trap is
part of
an antenna.
So do a single port test of the completed antenna, that's the real test.
Could be displayed as impedance, SWR, Smith Chart, whatever you are
comfortable with.
Look at each band individually, sweeping all of HF may not give enough
resolution to see resonances.

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