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Old June 10th 06, 03:07 PM posted to rec.radio.amateur.antenna
Jim - NN7K
 
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Default Noise level between two ant types

Not to mention that noise is normally a phenonmen
of the Vertical Plane (which , depending on how
steep your inverted "vee" is, will contain some
vertical component, while the yagi/quad is
Horizontal to the plane. This has been a factor
on vhf for years, as noise levels tend to peak
at 6 meters (50 MHz). The MAIN reason that F.M.
is Vertical polarized is that for mobiles, it is
easy to construct an omni-directional antenna.
Most vhf manuals detail this effect! Jim NN7K

wrote:
Ken Bessler wrote:

Take 2 antennas on 6m - one is an inverted V and the
other a 3el quad. Both are mounted at near the same
height and fed with about the same length of coax.

Is it normal for the quad to be quieter?



Noise almost always arrives from multiple directions and from different
directions than the desired signal.

It is normal for ANY antenna to be quieter when it is more directional.
As a matter of fact, it is expected that S/N ratio is a direct function
of directivity of the antenna as long as the noise and signal are not
coming from the same direction.

To answer your question, it would be very abnormal if your quad (or
Yagi or any other directional antenna) was noisier than a broad pattern
antenna like your Inverted Vee dipole.



73 Tom