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The accompanying file SOMNEC.FOR contains the FORTRAN source code for
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the SOMNEC program. The SOMNEC program generates grids used by the NEC2
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program for the Sommerfeld-Norton approximation to realistic grounds.
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I hand-coded the source code from the listing given in NOSC TD-116,
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Volume I, Part II, pages 390 -- 433. I changed the code given in the listing
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to enable interactive user input of relative dielectric constant, ground
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conductivity, and frequency in MHz. The source code as given relied on the use
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of a tape drive to accomplish communication of the results of the SOMNEC
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program to the NEC2 program (old-timers, takes you back, doesn't it?).
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I elected to accomplish inter-program communication on the DEC VAX and Unix
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workstations available to me by using a binary unformatted file. Hence the
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user is also prompted for a file name, and the grid arrays are written to the
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file. I also had to make changes in the NEC2 code, to tell NEC2 the name of
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the SOMNEC file, to open the file, and to read in the file contents. Users
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wishing to employ the SOMNEC code with implementations of NEC2 or NEC81
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expecting SOMNEC file input will have to determine the file type and format
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expected and recode accordingly. I eventually incorporated the SOMNEC
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program in NEC2 as a set of subroutines, and that is the version I am now
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using.
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The file SOMNEC_OUTPUT.TXT contains the results of a run of SOMNEC
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using the inputs in example 10 in Volume II of NOSC TD 116. Note the
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agreement with the results given on pages 154 -- 156 of Volume II. The
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time for execution of this case was 257 seconds on a DEC VAX 8600.
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On a Silicon Graphics 4D/440 workstation, I obtained around 100 seconds
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execution time for the same case, and I would expect tens of seconds when I
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port the code to a DEC AXP, as I will do soon.
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I hope this code is useful to you -- 73!
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George B. Christianson
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Princeton University Plasma Physics Laboratory
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gchristianson@pppl.gov
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(Amateur Radio NJ2P)
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October 5, 1994
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