NEC-LIST: antenna over ground using SOMNEC

I'm modeling a dipole over a ground using the programs "SOMNEC" and
"NEC-2". I would like to have more information about the height (h) of
such an antenna.

In the NEC-2 manual, part 3, the authors wrote :
1) "(h^2+a^2)^0.5 should be greater than about 10^(-6) wavelengths"
2) "the height should be at least "several times" the radius (a) for
the thin approximation to be valid". Please can you give me an idea of
the value of this relative term "several times" ?

The dipole I'm modeling is 6 m long and has a radius of 3 cm. Moreover
I use the EK card (Extended thin-wire Kernel) because the segments of
this dipole have a lenght of 10 cm, so that the (lenght/radius) ratio
is low. I excited this dipole with frequencies ranging from 2 MHz to
60 MHz (wavelenghts ranging from 100 m to 3.33 m over a ground with a
relative dielectric constant of 3.5).

In this case, are the results obtained with an antenna height beetwen
3.1 and 4 cm valid ? Or is this range of heights too low ?

For the 2 conditions in the NEC-2 manual stated above, the first
condition 1) seems to be verified, but I would like to know a little
more about the second 2) : What does "several times the radius" means
exactly and must this second condition be verified if using the EK
card ?

Thanks for your explanation, it will be of best use.

Best regards.

LUTZ Pascale

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| Pascale LUTZ | e-mail : pascale.lutz_at_univ-pau.fr |
| Laboratoire d'Imagerie Geophysique | |
| Universite de Pau | Tel: 33 (0)5 59 92 31 74 |
| et des Pays de l'Adour | Fax: 33 (0)5 59 92 31 86 |
| Avenue de l'Universite | |
| 64000 Pau | |
| France | |
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Received on Sun Apr 09 2000 - 12:25:09 EDT