NEC-LIST: NEC-2/SOMNEC error message?

Dear all,

I'm trying to model radiation patterns using NEC-2 and somnec for
Ground Penetrating Radar purposes. The antenna is a dipole over a
ground (relative dielectric constant=EPSR ; conductivity=SIG). This
dipole is 1 cm high, 1 m long and its radius is of 5 mm.

For the low frequencies NEC-2 returns the error message below although
the condition sqrt(h*h + a*a) > l*0.000001 is verified (h=height ;
a=radius).

error message : ROM2 -- STEP SIZE LIMITED AT Z =-2.68364E-07

The input file is :

CE 1 dipole
GW 1 11 -0.5 0 0.01 0.5 0 0.01 0.005
GE
FR 0 1 0 0 58 1.
EX 0 1 6 0 1 0
PQ
GN 2 0 0 0 12.5 0.1
NE 0 1 21 21 0. -20. -20. 0. 2 2
NE 0 21 1 21 -20. 0. -20. 2 0. 2
NH 0 1 21 21 0. -20. -20. 0. 2 2
NH 0 21 1 21 -20. 0. -20. 2 0. 2
XQ
EN

The error messages in the output files are for example : ROM2 -- STEP
SIZE LIMITED AT Z =-2.68364E-07

With a height of 1 m, there is no problem. However for a good
simulation of the reality, the dipole must be located close to the
ground.

Any suggestion to solve this problem will be of great use.

Thanks for the attention.

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 Mon Jul 10 2000 - 23:15:55 EDT