On Wed, 18 Mar 98 14:58:34 -0500 John Kaufmann <kaufmann@ll.mit.edu>
writes:
>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
>
C'mon John....you said nor explained nothing.
Does NEC-4xx accurately model on or near ground radials or not?? With
your MIT - MITRE involvement I think that you can answer this.
The bottom line for me is...do I want to spend hours dragging out wires
for under 1dB improvement...OR can I expect up to 5-6dB for my sweat?
Tnx Carl KM1H
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