Juergen_vonHagen wrote:
>
> hmmm, there is another great code, called FEKO by Uni Stuttgart and
> EMSS South Africa (http://www.emss.co.za) which is able to do very
> nice things. In contrast to NEC, it uses patches also in the EFIE,
> so open structures are possible without having the need to do
> wiregrid modeling. Included in the code is physical optics,
> geometrical optics and MOM, you can use them in a mixed simulation.
This is a good approach, and I am not doubting the efficiency of such
a procedure. My question would be: in this great code are the Green's
functions asymptotic in form for the canonical problems ?
>> The advantage ? Well, the computer resources required as frequency
>> goes higher remains constant for NEC-BSC, while it does increase
>> almost exponentially for NEC-MOM codes.
> so it does not increase exponentially, but only in a polynomial
> way.
My face is red. I was wrong as I did not recall the appropriate
chapter in Stutzman and Thiele very correctly.
>> This is not a problem with NEC-BSC or NEC-MOM, but a fundamental
>> numerical limitation with "exact" (MOM) and "asymptotic" (BSC)
>> formulations themselves.
> which remains true.
And is the underlying basis of the increase in computational efficiency
of "asymptotic solution based-codes" (like NEC-BSC3) as oppossed to
*purely* "exact solution based-codes" (like NEC-MOM).
>> So if you are working around 1 GHz and structures around you have mean
>> dimensions equal to or greater than 1*lambda, use NEC-BSC. However,
>> you can use the NEC-MOM code about this frequency (1 GHz) to verify
>> the results.
> or look at FEKO where you can mix PO, GTD and MOM for even enhanced
> accuracy.
I have a general observation to offer on this. PO, PTD, UTD (or GTD)
are "asymptotic" formulations with varying degrees of applicability
and accuracy. The "mixing" of PO, GTD is thus somewhat unclear to
me. (I do follow how MOM and GTD can be mixed as the Green's function
in the GTD (or UTD)is asymptotic and hence is guaranteed to save
computer resources as the wavenumber goes higher.
> cheers
> juergen
*************************************************************
Deb Chatterjee, Ph.D.
Assistant Professor, ECE Dept.,
University of Missouri-Columbia/ Kansas City (UMKC)
370-H Robert H. Flarsheim Science and Technology Hall
5100 Rockhill Road, KC, MO 64110-2499
tel.: (816)235-1276 (voice) || fax: (816)235-1260
e-mail: chatd_at_umkc.edu
Received on Thu Sep 23 1999 - 01:57:11 EDT
This archive was generated by hypermail 2.2.0 : Sat Oct 02 2010 - 00:10:39 EDT