RadioBanter - View Single Post - Given my restrictions, how can I improve my HF antenna?

April 8th 06, 01:17 AM posted to rec.radio.amateur.antenna

In article ,
(Dave Platt) wrote:

In article ,
Thomas anonymous wrote:

I'm renting a basement suite and have an Icom 706mkII & MFJ-949E antenna
tuner, and I need a better HF antenna arrangement than I already have
(without going to a tower, hi). I would like to run a balanced
feedline from the tuner to the feedpoint but the feedline has to go
from my shack to where the feedpoint is, and that involves crossing a
cement path --- in other words, because the feedline has to lie on top
of cement it can't really be anything other than coax.

You could make up a section of shielded balanced line, to get the feed
across the cement without having it couple messily into the ground.

A shielded balanced line can be made from two equal-length runs of
coax cable. RG-6 would work; aluminum-jacketed cable-TV hardline
might be even better from an electrical standpoint although its
rigidity might be inconvenient. Connect the shields/braids of the two
sections of coax together at each end, use the center conductors
to carry the signal, and fasten the two coaxes together in some
convenient fashion (an occasional nylon wire-tie would do, I believe).

The impedance of such a line will be twice that of the individual
pieces of coax - i.e. 150 ohms if you use RG-6. No need to worry
about matching it to the rest of the balanced feedline. You can use
300 or 450 or 600-ohm (nominal) balanced line where convenient, to
keep the losses as low as practical, and this 150-ohm shielded
balanced pair where necessary. The losses should be acceptable, and
will certainly be less than if you plumbed the whole distance with 50-
or 75-ohm coax.

perhaps just making a wood board or somthing to fill a few inches and
cut to allow the window to close on it, w/foam too and drill a hole in
the wood to pass the wire and have it centered enought away on all
sides from metal then it dosn't disturbe or damage the building/window
etc