I am beginning my planning and construction of a small loop antenna for 80
meters. The loop will be constructed out of 3/4" copper pipe, octagon
shaped, and have a perimeter of 72 feet. The plane of the loop will be
vertical and will be resonated by a variable capacitor in series with the
top pipe section. The voltage and current through the capacitor have very
large values.

See http://tinyurl.com/bwobb for more information. Any comments, thoughts,
and advice will be greatly appreciated.

John, N9JG

On Wed, 16 Nov 2005 19:33:51 GMT, "John.Gotwals"
wrote:

I am beginning my planning and construction of a small loop antenna for 80
meters. The loop will be constructed out of 3/4" copper pipe, octagon
shaped, and have a perimeter of 72 feet. The plane of the loop will be
vertical and will be resonated by a variable capacitor in series with the
top pipe section. The voltage and current through the capacitor have very
large values.

See http://tinyurl.com/bwobb for more information. Any comments, thoughts,
and advice will be greatly appreciated.

John, N9JG


That loop is detailed in chapter 5 of the ARRL Antenna Book (19th
ed.). Might be worth getting the book if you're going to build it.

bob
k5qwg

Thanks for the suggestion, and yes I have the book.

"Bob Miller" wrote in message
...

That loop is detailed in chapter 5 of the ARRL Antenna Book (19th
ed.). Might be worth getting the book if you're going to build it.

bob
k5qwg

On Wed, 16 Nov 2005 19:33:51 GMT, "John.Gotwals"
wrote:
resonated by a variable capacitor in series with the top pipe section.

Hi John,

The bottom would seem to be far more accessible and you should loop
feed the entire antenna (a loop inside the loop, that is) - Reg has
many times pointed out this matter of simplicity solves many
headaches.

73's
Richard Clark, KB7QHC

It seems to me that it's a lot easier, from a mechanical standpoint, to use
a simple gamma feed (without a capacitor) at the bottom of the loop. This is
a one band antenna, so finding an optimum match should not be that
difficult. If I feed the loop at the bottom with a gamma match, then
symmetry requires the capacitor to be at the top of the loop.

However, if using a second one-fifth sized loop as the feed loop allows me
to mount the capacitor at the bottom, then this type of design might become
attractive. It is not clear to me how easy it would be to keep the relative
positions of the two loops fixed.

"Richard Clark" wrote in message
...
On Wed, 16 Nov 2005 19:33:51 GMT, "John.Gotwals"
wrote:
resonated by a variable capacitor in series with the top pipe section.

Hi John,

The bottom would seem to be far more accessible and you should loop
feed the entire antenna (a loop inside the loop, that is) - Reg has
many times pointed out this matter of simplicity solves many
headaches.

73's
Richard Clark, KB7QHC