Vaughn,

It's quite easy: your best bet is the maximum length of wire you can keep
in your backyard AND as high up in the air as you can afford (trees,
towers, chimneys etc.)

To prevent RFI and TVI, make your antenna symmetrical. Feed it with an
open line, and connect the open line with your TX with an appropriate
coupler (the ARRL Handbook is a good source for information).

Please note you do not need to use a thick gauge of copper wire. Even a
thin gauge of stainless steel wire will do.

You will be pleased very much by the results !!

73 de PA0ARY

On Sat, 03 Jan 2004 18:38:59 +0000, Vaughn Combs wrote:

I have a few questions and I thought that this may be the group that could
help. I have a nice sized backyard and would like to construct an antenna
that would give me good performance on 80-10m bands.

The convenient dimensions would put a support (far end) at either 92 feet
from the back of the house (support exists that is about 15-20 feet up) or
120 feet from the back of the house (mast anchored to the other side of a
shed could easily be installed. Or a more inconvenient support could be
erected up to 300 feet out (no support buildings) at the absolute far end of
the property. The width of the property as seen looking out the back window
is about 65 feet (no supports existing on either side).

Special circumstances and constraints:

-- No tall trees on the property.

-- Attic shack (attic window is probably about 25 feet up). Need to keep to
the attic.

-- Cable run from back of house to operating position within the attic would
be approximately 25 feet

-- MUST eliminate RFI in the shack and house.

My current setup is an end-fed longwire that works well on all bands except
40m (rig shuts down as I am dipping the SWR to almost 1:1 ;-). I threw up
the wire as winter was upon me. I have been off the air for almost 10 years
and REALLY wanted to get on the air again.

While the longwire is performing quite well with the exception of 40m I am
getting a ton of RF in the shack and it is blanking out TVs and creating
loud humming in speakers with 100W from the XMTR. I realize that this is
most likely due to the fact that I have inefficient RF ground and I have cut
and run radial at 1/4 wave for each band and ran them under the eaves up
here in the attic. This has not solved the problem. I am friendly with all
of my neighbors and have visited them and did testing on the bands with them
on the phone. They are not experiencing any problems. My wife, while
understanding, would REALLY like the problem to go away ;-)

My main goal is to build an antenna that will solve the aforementioned RFI
problem and that will provide good performance given my constraints.

Any ideas would be GREATLY appreciated.

Many Thanks and 73,
Vaughn
N2BHA