Owen Duffy wrote:

Dan,

Some more information on expected ambient noise per ITU-R p.372-8 is in my
article at http://www.vk1od.net/fsm/FSAmbientNoise.htm . For 3.6MHz, it is
probably wise to expect ambient noise field strength somewhere around
6dBuV/m in 2kHz bandwidth in a residential environment. If an antenna can
develop more than about -130dBm in the receiver from that field strength,
the S/N should be ok on most modern SSB receivers which have a noise floor
somewhere around -136dBm. If you were in a quieter environment, you would
benefit from a better antenna.

Owen

Andy writes:
Thanks for posting the website, Owen.....
My comments were based on a residential/business site with a bandwidth
that
could accomodate AM, and I was generalizing .....

When I was designing LORAN (100khz) set sfor aircraft (TI2000) , I
needed to
find how small an external whip antenna could be... It turned out that
22
inches was sufficient, since a larger antenna which would convert more
signal, would also convert, proportionately, more noise......

I guess that's why whip antennae on AM car radio are only a couple
feet long, and why loopsticks work so well at AM broadcast.....

A nice article you wrote,.... thanks for giving the web reference...


Andy W4OAH, in Eureka, Texs