----- Original Message -----
From: "K4SAV" <RadioIR@charter.net>
>
> 80 meter inverted vee with apex at 100ft, 90 degree included angle,
> azimuth response at 10 deg el. Numbers are: Az angle in degrees,
> Horizontal component in dBi, Vertical component in dBi, signal to noise
> ratio in dB. 90 degrees is perpendicular the plane of the antenna.
> AZ Horz Vert S/N
> 90 -2.7 -100 97.3
> 45 -6.2 -9.3 3.1
> 25 -10.9 -7.4 -4.5
> 10 -18.7 -6.8 -11.9
> 0 -45 -6.4 -38.6
>
> 80 meter horizontal dipole at 100ft, azimuth response at 10 degrees
> elevation:
> AZ Horz Vert S/N
> 90 -1.1 -100 98.9
> 45 -4.9 -16.1 11.2
> 25 -10 -14.5 4.5
> 10 -18 -14 -4
> 0 -100 -13.9 -86.1
>
These results suggest to me that in an urban environment
where the noise is fairly isotropic (lots of small sources
coming from all directions adding up non-coherently) that
the dipole in general will be better than the inverted-vee
for receiving (unless the desired signal is in the null off
then end of the dipole). I've seen this in practice
comparing a 160 meter horizontal dipole at 90ft to a 80
meter inverted-vee at 90ft in an urban location (very high
man-made local noise floor). On 80 meters, 9 times out
of 10, the 160 meter dipole produces a significantly better
SNR on receive than the 80 meter inverted-vee. It could
be that the noise at this location isn't as isotropic as I
assume, but I am betting its the polarization characteristics
rather than the directivity of the two antennas that makes
the difference.
In a rural location where all the noise arrives via skywave,
I don't think it matters too much.
73, Mike W4EF........................
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