RadioBanter - View Single Post - best HF antenna system next to a trailer?

September 12th 05, 04:27 PM

On 11 Sep 2005 23:07:39 -0700, wrote:

I would like to work CW DX on 40, 30, 20, and 17 meters.

Hi OM,

Not 10, 12, 15, nor 60?

80 and 160 would be a bonus.

They would be a miracle - sometimes miracles are indistinguishable
from luck or accepting comes-what-may.

Probable options:

1) Load up the streetlamp with an antenna matcher, work against 180
degrees of buried radials out to 1/8 lambda.

How would the park owner feel about that? 1/8 lambda of what? 80M?

2) Solder a series of tin/steel cans (cantenna) using pocket torch and
copper tape to 1/4 lambda with added capacitance hat(s), brace the cans
against the ground and the trailer, work against 270 to 360 degrees of
buried radials out to 3/8 lambda.

Sure, it's been done, but more as a gag because so many simpler
options are available. It will need just as much guying as the next,
more conventional vertical anything. So why not just go out and get
that some nested tubular sections? Army surplus field antennas 40
feet high have been selling for $80 - $100 for years. And they come
complete with even the sledge hammer to sink the guy pegs.

3) Create a mast from 40 feet of metal pipe and 15 feet of wood rod,
brace against trailer burying pipe end 10 feet, mount an inverted vee
trap dipole in N-S direction for E-W DX.

Ah! 40 feet of metal pipe. Glad to see that the stack of cans has
an alternative. Well, this is a start for testing various designs
against.

4) Pair of masts on either side of the trailer, mount a delta loop
from each mast, feed one loop and use the other as a reflector.

An elaboration of the 40 feet of metal pipe.

5) Pair of cantennas on each side of the trailer, operating as out of
phase pair of 1/4 lambda verticals.

Dump the cans and stick with the 40 feet of metal pipe. But it seems
we got here by wanting an antenna that worked most the bands. The
"phase pair" is not that and it will probably have more effort
involved than perceived return. Certainly that is something that
never stopped anyone who starts this kind of project and it will offer
hours of diversion.

Which would be best?

The one with best DX. You could as easily ask which would be:
the easiest, efficient, practical, useful;
or to go with the antonyms:
the absurdest, illogical, impractical, tortured....

It all depends on wavelength and the terms flip from one category to
the next, appropriately.

Overall, the longest dipole you support as high as possible, with a
twin line transmission line to a tuner. Add a ground field so you can
tie the transmission line together to drive it against the ground for
the lowest band.

And where do I place the lightning arrestor(s)?

As close to your ground field as possible (with it, in turn, tied to
the ground of your panel per code) or you will become the Eternal
Flame.

73's
Richard Clark, KB7QHC