"Frank" wrote in message
news:t4okd.90482$VA5.33610@clgrps13...

"Frank" wrote in message
news:H4hkd.141267$9b.112169@edtnps84...
Modeled #14 AWG, copper conductor, 32ft monopole, 29 radials of 25ft, and
base 6" above (nominal lambda/1000) Sommerfeld/Norton ground of Er = 13,
sigma = 0.013 S/m at 1.8 MHz. All segments 6".

NEC2 computes:
Zin = 2.87 - j1358 Efficiency 92%

RADIALS2 computes (with radials 1mm below ground):
Zin = 1.55 - j1310 Efficiency 23.5%

Not a large amount of difference, but thought I had gotten closer results
with a different monopole, but seem to have deleted the code (Not sure
why such a large difference in efficiency). NEC2 is supposed to provide
a reasonable approximation of a buried radial monopole when at about
lambda/1000 above ground. Be interested in any comments, and what NEC4
provides if anybody has it.

73,

Of course the higher efficiency is due to NEC calculating only the I^2R
losses, and not the TRP. TRP should be fairly easy to calculate since the
pattern is "phi" independent. Have not checked to see if there is a TRP
card.
Note that a 32 ft monopole mounted on a perfect ground has an input
impedance of 1.58 - j1311 Ohms. The efficiency is reduced to 86% due to
increased I^2R losses.

Frank

From the calculated field strength (as a function of Theta) the TRP for 100
W input, which includes copper and ground losses, shows 27.4 W, or 27.4%
efficient. In very close agreement with the RADIALS2 program. The only
noticeable discrepancy appears to be in the real part of Zin.

Frank