On Dec 29, 9:45 pm, Roy Lewallen wrote:

Here are some numerical values to illustrate what happens to the
ground wave field..... Field intensities are shown at various
distances from the antenna. These are the entire field, including
surface wave. View with a fixed-width font.

Field strengths, dBi, are under each elevation angle:

-- Elev angle --
Freq(MHz) Dist(mi) 0 deg
....
1 1 4.0
1 10 -2.8
1 50 -18.7
______________________________

I thought it would interesting to compare the field strength values
for these parameters when using the FCC's propagation curves to that
which can be calculated using the antenna gains in dBi (not field
intensities) stated in the 3rd column above.

Here are the results (fixed font):

Distance to NEC Field
Dist, miles Calculated NEC Field per FCC Curves
1 170.6 mV/m 0.9949 miles
10 7.8 10.25
50 0.25 49.94

Agreement is excellent at 1 and 50 miles, less so at 10 miles.

RF