[MRCA] Antenna Technical Question

[J. Forster]

> ---------------------------- Original Message ----------------------------
> Subject: [MRCA] Antenna  Technical Question
> From:    "B. Smith" <smithab11 at comcast.net>
> Date:    Tue, February 18, 2014 8:48 am
> To:      mrca at mailman.qth.net
> --------------------------------------------------------------------------
>
> Can anyone explain the source of the compelling natural or perhaps
> unnatural force  that drives one to erect, take down, or modify wire
> antennas during the coldest and snowiest  months of the year?

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This question comes around every year.  IMO, it’s asked more often in jest
than seriously.  But good, serious answers exist.  Here are a few.  Every
one of these answers is true based on my personal experience.


1. DX propagation is best during winter, due to details of ionospheric
photochemistry and thermodynamics.  For this reason, most DX contests
occur in winter.  It is human nature to wait until the (figurative) last
minute to do a thing.  Hams postpone antenna work until they _need_ their
antennas to work.

2. Antennas are more likely to break in winter than in the three other
seasons combined.  Storms occur in all seasons, but winter storms are the
most destructive because ice and frozen snow increase the diameters of
wires and tubes, so wind drag is greater.  Ice and frozen snow also
increase the weight of wires and tubes.

3. Many “antenna” failures are caused by water getting inside the
enclosures of impedance-matching and/or balun transformers, chokes,
resonant traps, switches/relays, and tuners.  Such water problems are much
more likely to occur in winter, when diurnal temperature cycling more
often passes through the dew-point and/or the freezing point of water.  As
an enclosure cools in late afternoon, the air pressure within it drops; so
air, including water vapor, is drawn in.  Overnight, this water vapor
condenses and may freeze.  As the enclosure warms in the morning, the air
pressure within it rises; so air, including water vapor, is expelled. 
However, less water is expelled than was drawn in, because some water
remains in liquid or solid form.  Day by day, more water accumulates
within the enclosure.  When water penetrates electrical insulation,
failure occurs.  Water also causes corrosion, especially electrolytic
corrosion.

4. Antenna failures are caused by high-voltage arcing over the surfaces of
insulators that have been coated with semi-frozen snow.

5. In spring, summer, and fall, hams (like most other people) are more
likely to be doing other things, enjoying the weather, taking advantage of
nice weather to play, to work on the yard, to work on the house, go to the
beach/lake/mountains, etc.  In winter, hams (like most other people) get
cabin fever.  That is, they get tired of being cooped up indoors.  They
get restless.  They can’t work on the garden, work on the boat, reshingle
the roof, or paint the house.  So they’re more likely to work on their
antennas.

6. _Some_ people, including me, hate heat and humidity.  I _prefer_ to do
antenna work in winter.  I enjoy it because I’m not hot, not soaked in
sweat.  All my life, I have built antennas in winter because it is
_easier_ for me.  (YMMV.)

>From an antenna guru friend,

-John

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