Re: Availability of Mag Loop and other stuff...

Arv Evans
 

Jack

Since your loop is small it could be rotated and a remote receiver and antenna
used to derive a signal strength pattern.  This could be automated if you use a
stepper motor rotator and automated logging of the signal levels at various angles. 
Then you came up with the idea of counterpoises and possibly ruined it all because
rotating a counterpoise might be difficult at best.

I share Allison's thoughts that near-fields should be avoided because it could lead
to inaccurate results.  Have you considered using one of the many on-line remote
receivers for your tests.  This could get outside the near-field situation. 

Arv
_._


On Sat, Jun 1, 2019 at 8:17 PM Jack Purdum via Groups.Io <jjpurdum=yahoo.com@groups.io> wrote:
Good grief, guys, this is a hobby for me. Allison, are you really trying to be helpful here, or simply showing that you have a lot of RF experience? Perhaps the best solution is to do no testing and simply say we made contacts with it and leave it at that. Pretty hard to criticize the methodology when there's no information given. We have an EFHW available to us for testing, so that's what we're using. Also, there are a lot of hams out there using EFHW antennas so any testing we do with it will have meaning to them even if it does have a crappy radiation pattern for testing. If it's not ideal, so be it. My chances of renting two fiberglass crafts to sit on the Great Salt Lake loaded with a boat-load of equipment and antennas are about zero. Someone else with deeper pockets than I have will have to do that testing.

The good news is that if we do write an article on our ML experience, no one has to read it.

Jack, W8TEE



On Saturday, June 1, 2019, 4:17:30 PM EDT, ajparent1/KB1GMX <kb1gmx@...> wrote:


Jack,

the biggest issue is the 80-10 EFHW has a terrible pattern, broadside at 80m and by 20M
its a 4 lobe pattern with 10m its practically endfire.

That creates issues and questions for comparison as the EFHW is then rarely aimed at
the receiving station and hence you do not have a known comparison.

Generally when testing loops a loop of known performance are used but testing at HF is
never easy as the near field is at least 5 to 10 wavelengths or more and ground quality
dependent.  You want that distance to be able to see the total field.   The easiest rig
for that kind of testing is two fiberglass boats on calm salt water (an almost near
perfect ground plane).  Of course that does not include RF sources and calibrated
receivers and accurate GPS.

Allison

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