Ah but they have the first 35 feet vertical. I have lately wondered how far
one can get on 20m with an equivalent inverted L to scale ie about 4 inches
vertical with around 12 inches horizontal. - [ and a few ground rods driven
1" into the lawn ?] . Not an expensive experiment until the final blows up I
suppose and any suggestion that the radiation all comes from the feeder I
shall stoutly deny. even if the balun is taller than the antenna. Hmm..
back to the drawing board
Bryan
-----Original Message-----
From: Stewart Bryant <[email protected]>
To: [email protected] <[email protected]>
Date: 02 August 2003 17:22
Subject: Re: LF: Re: 500m drums of coax dipole
But compared to 2000m the 10 to 20m that most folks manage is still
small.
As I write this I look out at the farmers field behind my new house
reasonably high on the north downs. Perhaps I should take a reel of
cable down the edge of his field, and through the woods beyond.
I could not manage a dipole, but perhaps it is worth trying one of the
grounded at both ends, on the ground, loops that were talked about
in the early days.
Can anyone remember what sort of length one needs to start with?
Stewart G3YSX
captbrian wrote:
Is there the slightest evidence that 136 propagates (propogates?) by
scatter or reflection.? I assume most of a 2" high dipole radiation goes
straight up to Mars.
Bryan
-----Original Message-----
From: [email protected] <[email protected]>
To: [email protected] <[email protected]>
Date: 02 August 2003 11:47
Subject: LF: 500m drums of coax?
Are you making a coax dipole for 136?
73
John Rabson G3PAI
I've always wondered about dipoles / loops at 136k?
A 'dipole' just lying on rocky ground where the water table is many
metres
below the surface could be quite effective. The angle of radiation would
be
poor
but the efficiency may not be as bad as first suppossed. One advantage of
a
big antenna on the ground is that it can't fall down and, for the local
planning committe, it's less than 9 feet high.
Some time ago I tried to simulate this by making a dipole for 21MHz and
had
a
number of QSOs through it while gradually lowering it's height and
retrimming
as I went. I managed to work Romania were I sent "Ant dipole 5cm agl".
I
have no idea what the Romanian though of this madness and he didn't stay
around
long to find out.
Incidentally, at about 2 inches off the ground the antenna was resonant
at
about 20% less than it's normal 'free space length'. Never did find a big
field
to try it on 136k.
73
David G0MRF
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