If you look at Ken Norton's paper from the December 1941 Proceedings of
the IRE The Calculation of Ground-Wave Field Intensity Over a Finitely
Conducting Spherical Earth, he lays out the equations for the E field
from a vertical radiator for short distances (short enough to neglect
earth
Guy Olinger wrote:
We will run NEC4 near field calculations on a 1/4 wave radiator with 120
buried 0.4 wavelength radials at 1.825 MHz, soil char of (5, .13). Even at
30 (thirty) km the depth of the notch near ground is still increasing. ...
At 50 km out the minimum at 100m height is -28.69
On Fri, Oct 12, 2012 at 7:27 AM, Richard Fry r...@adams.net wrote:
There is little point in dissecting the far field tens of kilometers from
a vertical monopole to find the field remaining there at low elevation
angles, because that does not account for ALL of the fields radiated by the
According to antenna engineering textbooks (Kraus, Balanis. Johnson
Jasik etc), the free space, far-field radiation pattern is not a function
of the distance from the radiator, as it is in the near field. The
near-field/far-field boundary conventionally is defined as equal to
2L^2/lambda,
Perhaps a better definition of far field is the point of increasing
distance where the shape of a pattern calculated by a near field process
quits changing at angles and azimuths of concern.
Let's test this idea using the NEC4 near field table generator. We will
not change processes, using the
I believe the question was what happened to the curve if you went out to 30
km and a height of 5 km. To compare with the curve of 2.8 km and a height
of 500m. At 2.8 km there is a notch forming, already at -2.5 dB. But the
notch is NOT at the ground.
If one pursues this tack, assuming all
