[CQ-Contest] 10-meter contest; directivity or the lack thereof
k8do at diamondcs.net
Wed Dec 19 09:57:53 EST 2001
The amount of radiation/response off the back/sides of your beam is not as
miniscule as you imagine... Unfortunately, the ARRL method of depicting
beam patterns gives a highly distorted view of the relative amounts of
radiation... Every beam antenna is a 360 degree antenna, except some
directions are a bit more equal than others...
Also, there are many directions to/from which a signal can propagate to a
given part of the world, not just one direction so some of those 'off the
side' contacts may not be off the side...
> Early Sunday afternoon, I was surprised to find that my tribander stack
> seemed to have lost its directivity. The array was aimed about 45
> degrees, but I was also getting answers off the side, from the likes of
> VE4-7, WA, OR, all the way out to KH6! This went on for a couple of
> hours, till the Europeans were gone.
> A couple of explanations occurred to me:
> -- In this contest, people expect to be able to hear and work weak
> signals, so off-the-side QSOs happen all the time.
> -- Backscatter can enhance sigs in non-favored directions.
> Anyone got any better ideas? I'm just curious.
> 73, Pete N4ZR
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