At 12:21 PM 3/18/98 EST, Earl W Cunningham wrote:
>Regarding Tom W8JI's comments re his conversations with Roy Lewallen,
>W7EL about NEC-2: when he designed EZNEC, Roy incorporated a
>"high-accuracy" (NEC Sommerfeld) ground which he claims to be accurate
>for low horizontal wires down to .005 wavelength high (about 2.7 feet on
>160m).
>
>I may be wrong, but I thought that NEC-4.1 was supposed to be accurate
>for horizontal wires near, or in, ground. If so, Christman's comparison
>of EZNEC vs NEC-4.1 with near-equal results for elevated radial systems
>says that W7EL did something right when he designed EZNEC.
>
I have had some correspondence with Roy W7EL on the subject of accuracy of
the ground models in EZNEC. Roy told me that the lack of agreement between
the computer models and some of the measured data, like that discussed on
this
reflector, led him to doubt the accuracy of the EZNEC/NEC-2 ground models
for assessing the absolute performance of elevated-radial systems. Used
within
its limits, however, EZNEC is still a very useful and powerful design tool
which
I use extensively.
73, John W1FV
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