Nah-- Think is is referred to as " Fresnel Zones", and other
nomenclature- It has to do with multi-path - phase relationships
of the recieved signal- similar to the drive down a country road
at midnight, listening to an A.M. broadcast station (DX) fadeing
in-out - if you measure the distance between the 2 fades, it
equals 1/2 wavelength ! this effect works also in the verticle plane!
and, at vhf- the effect is quite noticeable in the fades (every 40
inchs at 2 meters, and about 18 inchs on 450) has to do with the
multi path signals arriveing in phase, or out of phase (cancelling
each other)! as info-- Jim - NN7K

Cecil Moore wrote:
Ken Bessler wrote:

I don't get it - the premium antenna worked better except for
hearing my friend, where it worked worse. Anyone care to offer
an explanation?


Perhaps there was constructive multi-path interference
on your friend's signal at the location of the lower
antenna but not at the location of the higher antenna -
or vice versa. Or your friend was not located in the
plane of maximum gain of the higher gain antenna. That
2.7 dB of extra gain at one take-off-angle comes at the
expense of reduced gain at a other vertical angles.

great explanation! I actually learned something. BTW, my answer was gonna be
,," majic"..


"Jim - NN7K" wrote in message
m...
Nah-- Think is is referred to as " Fresnel Zones", and other
nomenclature- It has to do with multi-path - phase relationships
of the recieved signal- similar to the drive down a country road
at midnight, listening to an A.M. broadcast station (DX) fadeing
in-out - if you measure the distance between the 2 fades, it
equals 1/2 wavelength ! this effect works also in the verticle plane!
and, at vhf- the effect is quite noticeable in the fades (every 40
inchs at 2 meters, and about 18 inchs on 450) has to do with the
multi path signals arriveing in phase, or out of phase (cancelling
each other)! as info-- Jim - NN7K

Jim - NN7K wrote:
Nah--

Nah?

this effect works also in the verticle plane!
and, at vhf- the effect is quite noticeable in the fades (every 40
inchs at 2 meters, and about 18 inchs on 450) has to do with the
multi path signals arriveing in phase, or out of phase (cancelling
each other)! as info-- Jim - NN7K

What you have described is constructive and destructive
interference - the same effect I described.

Cecil Moore wrote:
Perhaps there was constructive multi-path interference
on your friend's signal at the location of the lower
antenna but not at the location of the higher antenna -
or vice versa.
--
73, Cecil http://www.qsl.net/w5dxp


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