Topband: Antenna Signal/Nosie

[Bill Hohnstein K0HA]

I'm wondering if there's any equation or computer software which
compares the signal-to-noise ratio of two antennas under something
similar to the following scenario:
  There is equal noise (eg static) coming from all azimuths and
    elevations.
  How does the signal-to-noise ratio compare when trying to receive
    an additional signal coming from a single azimuth/elevation
    which is on the main lobe of the antenna to another (or
    isotropic) antenna?
Perhaps it would be something like comparing the root-sum-square
values that do NOT include the main lobe along with the gain
numbers(?).
I thought of this after seeing the pattern of two different antennas
with nearly identicle shape, just one 2 dB stronger in ALL directions.
Doesn't seem like the antenna with the gain would improve signal-to-
"noise picked up by the antenna" ratio on receive.  A number like I
described would be useful in comparing two more diverse topband
receive antennas...

73,  Bill     K0HA



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