As I sit here not participating in the Jan VHF QSO party partially due
to a cold but mostly due to freezing rain, I wonder. I wonder what
stories and advice the group has about this sort of situation on VHF and up.

What sorts of design and fabrication details work to make antennas
perform well in environmental extremes?

tom
K0TAR

On Jan 23, 10:39*pm, tom wrote:
As I sit here not participating in the Jan VHF QSO party partially due
to a cold but mostly due to freezing rain, I wonder. *I wonder what
stories and advice the group has about this sort of situation on VHF and up.

What sorts of design and fabrication details work to make antennas
perform well in environmental extremes?

tom
K0TAR

Several years ago the only thing I had working until after the thaw
was a 20m square loop.

Jimmie

On Jan 24, 3:39*am, tom wrote:
As I sit here not participating in the Jan VHF QSO party partially due
to a cold but mostly due to freezing rain, I wonder. *I wonder what
stories and advice the group has about this sort of situation on VHF and up.

What sorts of design and fabrication details work to make antennas
perform well in environmental extremes?

tom
K0TAR

heated radomes

"tom" wrote in message
. net...
As I sit here not participating in the Jan VHF QSO party partially due to
a cold but mostly due to freezing rain, I wonder. I wonder what stories
and advice the group has about this sort of situation on VHF and up.

What sorts of design and fabrication details work to make antennas perform
well in environmental extremes?

tom
K0TAR

Agree....
No way to participate this year.
Have so much ice hanging I dare not move anything.
Lost the 40 and 80 meter inverted vee set up yesterday.
All three towers and the ground mount 160 vert are intact, so far.
Wind is howling, power is on again off again.
Hoping for the best at this point.
Northeast Montana is not a nice place to be right now.

Sam - K7SAM

In article ,
tom wrote:

As I sit here not participating in the Jan VHF QSO party partially due
to a cold but mostly due to freezing rain, I wonder. I wonder what
stories and advice the group has about this sort of situation on VHF and up.

What sorts of design and fabrication details work to make antennas
perform well in environmental extremes?

tom
K0TAR

Up here in Alaska we use covered Rotators, Bearing Shields, Low Temp
Freezer Grease, and heated Radomes to keep things working clear down in
the -60F range. Freezing Rain means you just have to keep the rotator
moving back and forth, every few minutes, to keep the Ice from building
up on the rotary sections....

--
Bruce in alaska
add path after fast to reply

On Jan 23, 7:39*pm, tom wrote:
As I sit here not participating in the Jan VHF QSO party partially due
to a cold but mostly due to freezing rain, I wonder. *I wonder what
stories and advice the group has about this sort of situation on VHF and up.

What sorts of design and fabrication details work to make antennas
perform well in environmental extremes?

tom
K0TAR

I'm thinking of what we did in the Navy: Encapsulation of one sort or
another. Radomes got mentioned already so I'll add rubber boots over
connectors and a generous coating of Scotchkote (or equal) over
exposed hardware.

Military antennas are usually over-built, as are the mounts. They
WILL stay together in one piece and they WILL stay up or somebody's
going to hear about it! For hams in vicious-weather zones, maybe it
means using plumbing pipe masts instead of thin-wall galvanized
tubing. Maybe it means more guy wires. Maybe it means paying ten
times extra to buy the absolute toughest item you can find. Maybe it
means buying something tough -- something made for a nearby commercial
band -- and laboriously modifying it to work at 2m, 220 or 440.

Without intending to demean any single approach, you may be facing a
tradeoff: Do you need to build a $2000 indestructible antenna setup
or can you replace a $300 one a few times? When the welfare of 6000
men on a billion-dollar ship is involved, the Navy's choice is easy.
For us hams, not so easy.

Aside: Wire antennas (not what you asked) usually had a "sacrificial
link" in the elements. In case of severe stress due to wind, the link
would part, putting some slack in the element but not bringing it
down. Until it was repaired, the antenna didn't tune quite like
before, but you could still get a match. The link was variously also
called the "weak link" or the "breaking link."

Emergency fallback (of which I have several) is the attic antenna.
The wet/icy roof attenuates the signals but it's not a blackout.

Sal
KD6VKW

I suggest getting in touch with your local repeater clubs. They will
have learned lots of techniques to make antennas survive in tough
mountaintop environments.

Roy Lewallen, W7EL

tom wrote:
As I sit here not participating in the Jan VHF QSO party partially due
to a cold but mostly due to freezing rain, I wonder. I wonder what
stories and advice the group has about this sort of situation on VHF and
up.

What sorts of design and fabrication details work to make antennas
perform well in environmental extremes?

tom
K0TAR

Well I thank everyone that has answered so far. And don't stop.

I am getting answers that aren't quite for the question I thought I
asked, and that's a good thing.

Thanks!

tom
K0TAR

tom wrote in
t:

I am getting answers that aren't quite for the question I thought I
asked, and that's a good thing.


I wrote something long, then deleted it, but one core idea persists...
Instead of going for rigidity and mass, you could try flexibility and minimal
mass, like a reed, feather or twig in principle. I made a 35 foot 'mast' for
an FM reception 1/4 wave dipole, from scrap. It lasted 15 years so far, and
might go on a lot further yet. It flexes to absorb wind blasts of up to 80
mph at times, or bird impacts, and is guyed (by its own coax plus a couple of
lengths of burglar alarm cable) at a 'static' node like that of a plucked
string, to minimise stress on guy wires. If any part gets hit, the whole of
it takes the strain. It looks like crap but it works and even though we don't
get heavy ice it would just crack and fall off it periodically if it got any.
Natural motion and flexing would see to that. I got the idea from seeing how
well reeds will stand long after winter hits them, and from realising that
the dynamics in the aluminium were similar. Its height is several hundreds of
times its width, and even if I'd had to scale that up to something much
taller, intended to bear more load, I think it might still work better than a
rigid tower. But it would be useless for strongly directional antennae.

Lostgallifreyan wrote in
:

tom wrote in
t:

I am getting answers that aren't quite for the question I thought I
asked, and that's a good thing.


... I got the idea from seeing how well reeds
will stand long after winter hits them, and from realising that the
dynamics in the aluminium were similar.

Crucial detail that did not survive the long reply I did not send, or get in
the one I did send: The aluminium was angle-sectioned, and used torsion as
well as bending to absorb force.

The insulated spacer and mount (crudely hacksawed hardwood from an old chair)
for the vertical dipole would damp the oscillations like a kind of 'anchor'
against the wind. The only time anything broke on it was a guy wire when mast
torsion made it bend and fatigue at the attachment point, but the mast never
fell even during the wind that did this to it, and this weakness can be
easily designed out. The metal mast never fatigues because it never flexes
beyond its natural spring tension at any point. If it did, it would have
fallen in weeks instead of lasting many years. The load at the top is only
about a half-pound, but the rest of the mast is less than double that, so
it's very efficient and cheap.