[TowerTalk] Practical Ground Screens for NVIS antennas

[Mark .]

Hi All,
All this talk lately of NVIS antenna work goes along with some antennas and 
masts I have been building lately to enjoy casual, portable hamming, with 
some emphasis on cheap antenna plans for a cheap emergency 80 trunk antenna.
So far, results have been quite good using 18ga lamp cord or speaker cord, 
using a 30' or less of the unzipped portion as a feedline, to a 4:1 current 
balun and then connected to the mobile HF rig.

I once read that an old trick for boosting the efficiency of horizontal 
antennas over questionalble ground was to run a series of radials along the 
ground parallel to the antenna.

For instance, if the antenna is a flat-top or inverted Vee, run 4-5 radials 
parallel to it along the ground, spaced 10-15  few feet apart.

This is pretty easy to accomply by unrolling precut wires from a homemade 
spool (you can get free plastic spools by asking for the empty ones at the 
home stores from their rotary wire supply racks).

What is an effective placement for such wires under the antennas? Any rules 
of thumb for length and orientation?

If separate wires, do they need to be approximately 5% longer than the 
driven antenna to act as reflectors?

It would be convenient to just have a long wire on a spool and lay out a 
zig-zag pattern around temporary stakes, such that you could just walk 
around and pay out the line from the spools. Winding them up would be a 
snap, too.

Thanks for your ideas.

--...MARK_N1LO...--