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Old November 1st 07, 12:19 AM posted to rec.aviation.homebuilt
Vaughn Simon
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Posts: 735
Default ELT antenna in composite planes.


wrote in message
ups.com...
The radiation gain in larger
antennas comes from directionality and not from nothing


Yes, but in this case, we are comparing a shortened (ducky) antenna to a 1/4
wave antenna, not a gain antenna. A 1/4 wave antenna has a pretty high angle of
radiation. I raised my eyebrow at Jim's estimate of 15 db, but when you start
adding factors, (eliminate the loss of the stubby antenna, antenna in the clear
outside of airframe, elevated antenna) you could end up with more difference
than you think.

You are correct that a long antenna gets its gain from decreasing the angle of
radiation and concentrating more of the signal at (or even below) the horizon,
but I have never seen a gain antenna used for an ELT, have you?

Vaughn (WB4UHB)