[Elecraft] Good Low Horizontal Loops - questions

[kc4kgu@EnterZone.Net]

On Wed, 7 Aug 2002, Lloyd Lachow wrote:

> I could probably string a roughly circular 1K' loop on
> my lot, through the trees, with an average height of
> about 50'. Here's what I need to know, though:

Make it 1080ft and you've got a nice 2f loop for 160m!  (Not that it
wouldn't work very well at 1000ft)


> when feeding the loop, is the loop broken, with one
> side of the feedline going to each side? 

Yes.

> If so, is the distance across that gap critical?

Within reason, I don't think so.  How much of a gap were you considering?


> What types of feedlines would work - which would be best?

That is a matter of great debate.  I personally use coax with great
success.

> Can I use twinlead?

I've seen it done with good results.

> Would I need a balun, an rf choke, or whatever?

That depends again.  A full-wave loop has a feedpoint impedence of about
100-ohms.  If you are going to be operating at resonance, a 2:1 balun will
allow you to use regular coax to feed and maintain great efficiency.  With
that said, does anyone know where I can find some 100-ohm coax?

 If you're going to use this antenna on multiple
bands, a balun may hurt efficiency.

> My rig is a K1 with KAT1, 40-30-20-15. Would one end of the feedline
> go to the center conductor, and one to the ring?

Yes.

> Would I need counterpoises? 

No.

> Will the feedline radiate? 

If you're operating away from resonant frequency of the loop, using
open-wire, twinlead or ladderline, yes.  It may even do so with coax but,
not as noticable.

> Is it ok if it does? 

That is up to you.  I personally try to keep my feedlines as feedlines and
radiators as radiators.  Some people enjoy this effect to load antennas on
multiple bands.

> importantly: I'm now using a longwire of about 200' that goes every
> which way, and works very well - good reports all over Europe, down to
> Central America, and domestically. Should I be satisfied with that,
> and cease this endless restless quest for gain?

I'll personally never be satisfied.  I love working with new antenna
designs though.  You loop and longwire WILL interact with each other
though so, keep that in mind.


73 de John - KC4KGU
K2/100 #2490