In a message dated 98-03-18 10:27:52 EST, you write:
<< Re..your other post and the April '98 QST comments by N6BV... Does not
the military use NEC-4xx to model their field installed and stealth
antennas? The question remains; are those models accurate to within <
1dB?
>>
Just because the military, or any other government entity, uses NEC-4 does not
mean that the results are absolute in the physics lab sense... It just means
that it is the best that we have available at any price...
I will note parenthetically that my antenna installations have benefited
tremendously from the use of ELNec/EzNec... I have been able to tune the
elements and get the expected patterns with less hair pulling and muttering
than in the past..
I have noted that the closer to the ground I get the further the element
lengths (as finally tuned) vary from the predicted length (no surprise
there)... Since I use the model to give me reactance values and suggested
lengths, I simply install at the modeled length and then tune each element to
the modeled reactance using the Autec RF-1 (primarily, but also the MFJ noise
bridge, the grid dipper, etc.)... Since the lengths and reactances are in the
ball park on initial installation, hitting the final values is much easier
with the model, than without it...
Denny
--
FAQ on WWW: http://www.contesting.com/topband.html
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Problems: owner-topband@contesting.com
|