[600MRG] Loops and ground loss

[John Andrews]

An article in May, 1936 Proceedings of the I.R.E. (the famous Armstrong 
FM issue) discussed the use of loop antennas in aero beacon 
transmission. At the end of the article, mention is made of untuned and 
tuned screens under the antenna. Some considerable reduction of 
feedpoint resistance could be achieved, particularly with tuning. By 
"tuning," I'm guessing that they used an inductor between the lower run 
of the loop and the ground screen to parallel-resonate the capacitance 
of the loop to the screen. I've never seen the results of any further 
work done on the subject.

John, W1TAG

On 3/3/2017 5:51 PM, Rudy Severns wrote:
> Hi Pat,
>
> I've only casually modeled ground systems for vertical loops so can't claim any expertise.  AS a first guess, if you want to install a mesh under the loop you want the mesh width to be maybe 1.5 or 2X the loop width but the mesh needs to extend perpendicular to the plane of the loop at least 3X the loop size.  That's just a first thought, more careful modeling is needed to really define the performance improvement versus mesh dimensions. One point, you don't need a small mesh like chicken wire, a mesh cell a couple of feet on a side should work.  I have some notes on mesh dimensions versus soil characteristics which I don't think I've published. I should clean it up a bit and post it on my web page if anyone is really interested.
>
> Of course this size ground system is still a pain, partially defeating the reasons for using a loop in the first place!
>
> We have the modeling tools to a good job of investigating loops with ground systems but I just haven't had the time since I haven't been a loop user.  There have of course been many articles on transmitting loops but scant discussion of associated ground systems.
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