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chuck chuck is offline
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First recorded activity by BoatBanter: Mar 2007
Posts: 18
Default Tilted SSB Antenna

On Wed, 10 Jun 2009 06:00:40 -0500, Geoff Schultz
wrote:

I was recently corresponding with an individual regarding reefing points
and sent him a back-lit photo of the sails. While I was looking at it, I
realized how much the whip SSB antenna is tilted backwards (about 10
degrees), and was wondering what effect that tilt would have.



As a vertical antenna departs from true vertical orientation, the null
at 90 degrees (straight up) begins to fill in and the horizontal
pattern begins to show some directivity.

The effect is quite significant at a tilt angle of 15 degrees.

As others have pointed out, you probably won't notice the differences
since before and after comparisons are usually inconvenient.

OTOH, you could use the effects to advantage at the lower frequencies
for communicating over distances from 50 to several hundred miles.
Energy radiated directly overhead is reflected closer to your vessel
than energy radiated at angles from 5 to 45 degrees. To make best use
of this (Near Vertical Incidence Skywave) you might want to tilt your
whip way over (assuming mechanical feasibility) to nearly horizontal.

An internet search on NVIS will fill in the details.

Good Luck,

Chuck