On 6/14/2026 11:49 AM, JC(Jose Carlos) via Topband wrote:
There is a very important note about the man-made noise, the ground propagation
works like a filter and 99% of the noise you receive is vertical polarized. It
is possible to reduce almost to 20 db using a horizontal antennas.
73's
JC
N4IS
I experimented with a horizontal square loop antenna, 50x50 feet, and 30
feet high. Listening at the high end of the AM BCB band to local
stations within ground wave range (up to 25 miles) it showed remarkable
suppression of those signals during the day time. OTOH, it worked fine
on skywave at night for receiving the Mexican station on 1700 kHz.
In some cases, distant stations that had significant QRM from local
stations on their same frequency when listening on a vertical were Q5
copy on the horizontal loop due to lack of local QRM. So I think this
confirms what N4IS was saying.
It was also interesting that it didn't seem to suffer from pickup from
my 106 foot tower that was "too close" to it for 160 meters. Other 160
meter antennas definitely exhibited pickup from the tower if too close
to it. (That tower does not have 80 or 160 meter antennas on it).
By the way, I used to use a low(30 ft) 80 meter cloud warmer as a 160
meter receive antenna. It often worked pretty well, but it didn't
exhibit same the suppression of local signals that the horizontal loop did.
Rick N6RK
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