Re: [IRCA] Questions about the indoor SuperLoop

["Kevin S" <satya@xxxxxxxxxxxx>]

Hi Dave/all:

1. The Super Loop is corner fed, so the resistor and transformer are in
opposite corners along the bottom.  Midway up the verticals would make it
a Flag - see the diagram at:
http://www.qsl.net/wa1ion/flag/flag_antenna.htm
I've never heard of one fed at the top corners - my guess is that it
wouldn't work because the Super Loop looks above the horizon in the "z
direction", with a max at about 20-30 degrees up, so a top-fed loop would
presumably look into the ground, since it is essentially a Super Loop
turned upside down.  See the first pattern diagram at
http://k9zw.wordpress.com/2007/12/22/the-new-waller-flag-antenna/
to see what I mean; this is a fairly representative "z direction" plot for
these antennas.

2.  If you lay it down, both my intuition and EZNEC say that it turns
omnidirectional, and being so close to the ground would make the gain
quite poor.  So, it would be great if it were a viable option, but sadly
not.

3.  I tried a TV transformer once - the ferrite material in those are
designed for VHF-UHF frequencies, not MW frequencies, and so you get
dramatically less signal transfer.  With a small, unamplified loop, the
results would probably be unusable.  Getting a J-type toroid or similar
from Amidon is the way to go, and winding it takes about 5 minutes.

As for where to put it, I would suggest making a 5x5 foot or so portable
loop out of PVC, similar to the ones I have pictured in the article, and
move it around the house to see where it is in your house that will work. 
This would avoid erecting one out in the garage only to find that the
structure of the house isn't amenable to the antenna.  Try to place it
near external walls with minimal roof and second/third stories overhead.

Good luck!  It's made a huge difference for me.

Kevin


> Hey Kevin;
>
> I have a couple of questions about your intriguing experimentation from
> the article "Small Terminated Loop Antennas."
>
> 1. What differences would the location of the feed point and termination
> resistor make.  i.e. What about them being at the top corners or midway
> up the "verticals"?
>
> 2. The various loop antennas, such as the KAZ, SuperLoop, EWE Flag and
> so on are all arranged on a vertical plane (for lack of better
> phrasing).  What if you simply laid the loop on the ground?  Would that
> work, with the antenna now being horizontal?  Would the null still be at
> the potentiometer and the signal still be at the feed point end?  That
> way you could use an open field, side yard or whatever and not need
> supports of any kind.  Of course, I dunno if it would work. :)
>
> 3. Transformer on the feed point - What signal degradation / mismatches
> would occur by simply using a TV 300 Ohm / 50 Ohm transformer?  IIRC, CT
> DX'er Bill Nollman (WTFDA list) erected a "down and dirty" flag last
> Fall and all that he had at that time was a 300/50 TV antenna
> transformer.  Could I get by with that just to get a unidirectional
> pattern?
>
> When I first saw the webpage about David Hamilton's "Slinky Loop," I
> thought that it would be cool to shove the Slinky inside of the PVC and
> just lay the frame (with the antenna inside) in the garage when not in
> use .  Now that I have read your article, I think that the big wall
> inside of my garage would probably support a 7' X 8' loop, just strung
> from insulated hooks.  I won't be able to do any preamplification but it
> sounds better than the Figure-8 pattern that my old Sanersino or my yet
> to be built Crate Loop would provide.
>
> Thanks again!
>
> 73,
> Dave in Indy
>

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