[TowerTalk] NEC2 Visualization
Kenneth Earl Harker
kharker@cs.utexas.edu
Mon, 4 May 1998 12:16:48 -0500 (CDT)
Let's try this again. I guess my subscription to the list hadn't been
approved completely the first time I sent it or something. I got a bounce,
but it might have propagated through the list already - my apologies if
people get this twice. I know it's not directly related to towers,
but I was encouraged by a list member that it would find good audience here.
>
> I am working on a term project in my visualization (computer graphics)
> class this semester involving the visualization of certain aspects of the
> radiation pattern of antennas modeled with NEC2.
>
> (http://www.cs.utexas.edu/users/kharker/antennavis/)
>
> At the moment, we have created a small application with a main window
> in which the graphics happen and a few buttons and slider bars and whatnot
> below it. The program loads in a .nec file from disk, draws the antenna
> in the main window from the data in the GW cards, and puts in boom, antenna
> mast and groundplane objects in the case of a yagi (I haven't tried this with
> other types of antennas just yet.) Currently, we can visualize the
> antenna's gain pattern as well as its polarization sense pattern, and we're
> aiming to visualize numerous other aspects of the antenn radiation field
> as well.
>
> In all the images on our web page, the color green indicates that NEC2
> reported a LINEAR polarization sense at that point in the pattern. White
> indicates RIGHT sense and blue indicates LEFT. I find it very interesting
> that the pattern is symmetric, but the polarization sense pattern looks very
> asymmetric.
>
> Now, to my questions; I'm not especially knowledgable about antenna
> modelling, having learned most of what I know for this particular
> project. Given output like what I'm attaching below, what would you
> like to see graphically visualized? Gain, of course, we're already doing,
> and polarization sense is probably easy. Would visualizing POLARIZATION
> TILT be useful? PHASE DEGREES maybe? Any other ideas?
>
>
> - - - RADIATION PATTERNS - - -
>
> - - ANGLES - - - POWER GAINS - - - - POLARIZATION - - - - - - E(THETA) - - - - - - E(PHI) - - -
> THETA PHI VERT. HOR. TOTAL AXIAL TILT SENSE MAGNITUDE PHASE MAGNITUDE PHASE
> DEGREES DEGREES DB DB DB RATIO DEG. VOLTS/M DEGREES VOLTS/M DEGREES
> 90.00 .00 -999.99 18.86 18.86 .00000 -90.00 LINEAR 0.00000E+00 .00 7.20823E+00 98.52
>
>
> Also, is there an easy way to determine in a .nec input file where the
> electrical center of the antenna is? RP output data is given in polar
> coordinates, presumably centered at the lectrical center of the antenna,
> and I'm interested in knowing where the appropriate place to locate the center
> of our rendered pattern; presently we're putting it at the physical center,
> which is easy to determine.
>
> Finally, the application we're working on is currently only running on
> Silicon Graphics IRIX boxes; it should be possible to recompile it without
> modification for Linux and other UNIX boxes, and in principle there's no
> reason we couldn't get it run on a Windows box eventually (I think - my
> knowledge of Windows is marginal at best.)
>
> I'm interested in any feedback/suggestions/comments.
>
> (http://www.cs.utexas.edu/users/kharker/antennavis/)
--
----------------------------------------------------------------------------
Kenneth E. Harker "Vox Clamantis in Deserto" kharker@cs.utexas.edu
University of Texas at Austin Amateur Radio Callsign: KM5FA
Department of the Computer Sciences President, UT Amateur Radio Club
Taylor Hall TAY 2.124 Maintainer of the Linux Laptop Home Page
Austin, TX 78712-1188 USA http://www.cs.utexas.edu/users/kharker/
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