Topband: Antenna Advice Plus K9AY Questions
jim at audiosystemsgroup.com
Fri Sep 7 11:22:17 EDT 2007
On Thu, 6 Sep 2007 21:44:38 -0500, Scott WA9WFA wrote:
> Why couldn't I just attach an Advanced Receiver Research
>preamplifier to the 160 meter inverted vee to achieve that 1 - 2
>S-unit improvement? ARR is suggesting one could see 6-14 db
>improvement in signal to noise ratio. Thats 1-2 S-units.
Preamplifiers improve the signal to noise ratio ONLY when the
noise that limits your reception is generated within your
receiver. This is virtually never the case on the lower frequency
ham bands -- the noise picked up by your antennna is always louder
than the receiver noise.
The noise you are trying to reject is atmospheric noise (static
from thunderstorms), noise generated on power lines, and noise
generated by equipment in your home and the homes of people living
around you. This noise comes in on your antenna. A receiving
antenna rejects noise by providing directivity or polarization or
both -- that is, it picks up signal better than it does the noise
if you point toward the signal and away from the noise.
I'll let someone who knows the loop antennas better than I do
answer your other questions.
Jim Brown K9YC
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