[Moon-Net] 2M antenna matching Data
radio.ku8l at gmail.com
Tue Nov 8 15:44:27 CET 2016
Thanks for all the comments and directions folks:
Regarding the data and its presentation, I can only say I copied it
directly from the dispaly on the software utility. Some of it I
understand, and some not so much. I am a newb with the Smith chart.
The software is a data sampling and control utility for the T100. It
collects sweep samples over a range of frequencies and step sizes and
loads them to a CSV file. They are then used to plot a smith chart as
well as an SWR, RL, and R+Jx charts.
I believe the G is for Gamma which is (I think) the 50 ohm Smith
normalized values of ZL. I also think the "angle" shown is the angle
of the vector at the given frequency and as the G point approaches 0+J0
the angle becomes meaningless due to the minimum sample resolution (25KHz).
Anyway. I have been using these two antennas for 2+ years and yes they
are as near identical as my machinist skills (substantial) could build
them. The T match jumpers are at the ends of the T bars as someone
They are oriented in the proper phase, and I cut the jumpers to less
than +- 1/16" from same pc of LMR-400 Brand new. My divider is one of
the 1/2 WL (1/4 +1/4) from square tube
THey system has about 28 initials on it but perhaps I am still expecting
too much from the pair. During the first period of the ARRL weekend
past, I could not detect a single station, including the mega stations
which were operating. Even when they worked, stations rarely had a
hard time detecting me, but I can barely see a trace for them. System
still shows less than about 1.2:1 SWR.
So I decided it was time to start at the top and see if something is
amiss...and it appears that, so far, not the antennas or feed+divider.
I am next going to check the TR relay(s) and will be working agin for
the ARRL weekend in 2 weeks. All the leaves are off the trees so that
may help a little.
Prior I will do some noise floor tests with the 50 ohm LNA terminated
and see what it looks like.
Again, thanks for all the support.
As an aside, I believe my issues previously noted regarding the big KW
paging system a mile away on 143.9 has been resolved. It looks like the
last of the antennas listed on that site have been migrated to DMRS on
800MHz. So I no longer see any of the intermod junk.
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