Colin, thanks for this info I will save it.


Junior Lolley KG4itd
Liberty County E. C.


-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of colin McDonald
Sent: Tuesday, January 04, 2011 1:08 PM
To: [log in to unmask]
Subject: loop formula

butch and everyone interested:
a typical HF sky loop, or loop type antenna is calculated for length by
using 1005 divided by the lowest desired operating frequency.  This will
give you a full wave radiator on the lowest frequency.
In juniors case, the formula was something like 1005/3.7 equaling around 271
feet.
acording to a very comprehensive article I just read, you can set up a sky
loop in several different configurations from circular, to square, to
rectangular to triangular, and either horizontally, or vertically.
The feed point location doesn't really matter with a single horizontal loop
as where ever the feedpoint is, it's still a loop as the article says.
A square loop, that is, the calculated formula divided by four and each side
being that length, will typically present around 120ohm impedance at the
feed point...so not so far off from say an inverted V or dipole.  The
article explains that you can use a balun or not, depending on your
preference, but one is not necesarily required for the antenna to match and
perform.
these antennas work very well on harmonically resonant frequencies, so
that's why if you build one for 80M, it will perform well right down to 10
meters, and likely beyond.
According to this author, the configuration that junior has now got set up,
is pretty much a perfect senario as far as Height and configuration of the
loop goes.
No wonder it works so well.
here is the link to the article that goes into more detail about loops and
so on:
http://www.qsl.net/kd4sai/loopant.html

73
Colin, V A6BKX