[Elecraft] K2 + ATU + Loop antenna in the attic

[Wayne Conrad]

My radio (K2 with the internal ATU) hasn't shipped yet, but that 
shouldn't stop me from putting up an antenna, right?  If only I knew 
what to put up, that is.  That's where I'm asking for help.

I want to start out with an loop antenna in the attic.  Why loop? Mostly 
the very American idea that more wire must be better, plus it's 
balanced--I hope to not need a separate RF ground, or counterpoises, or 
any of that jazz).  Why the attic?  So I don't have to worry about 
lightning protection, and because it ought to be incredibly cheap to put 
up.  I've spent every dime I have on the radio, you see.

The house is the usual ~60' x ~30 feet and "L" shaped, single story, and 
the major axis is North/South.  The attic is full of trusses and 
fiberglass, but I can get to most of it, sometimes slithering on my 
belly like a snake.  There are the usual electrical wires, network 
cabling (OK, maybe not everyone has CAT6 in their attic), TV coax, and 
AC ducts going hither and thither.  My shingles are asphault.

I have no idea what band or bands I'll be on.  I don't even have my 
license yet.

My thought is that I run the loop around the perimeter of the attic, as 
close to the eaves as possible.  Over the radio bench, I'll punch a hole 
in the ceiling and drop feedline down the wall.

I was thinking of open-wire feeder, because I "read on the internet" 
that it might be better for this application.

It occurs to me that I could omit the 4' of feedline and just drop the 
two wires down.  Using the self-adhesive conduit that the hardware store 
sells, I could keep those two wires at "an appropriate distance" from 
each other, and white conduit looks better against a white wall than a 
black cable.  I don't know if that's a good idea, or what "an 
appropriate distance" would be.

I don't know if I need a balun, or even what kind.

I don't know whether I need to keep the antenna wire off of the rafters 
with insulators, or can I just let it lay there.  Nor do I know if the 
answer to that question changes if I eventually go QRO.

I don't know if the length of the loop matters.

As you can tell, the ratio of things I know to things I don't know is 
pretty small.  Can you please help me improve that ratio?

Thanks, and best regards,
Wayne Conrad