"Arun S V" wrote in message
...
Hello all the FDTD experts over there ,

I am starting out on my class project which requires me to
write
a 2D FDTD code.I am thinking of doing it in Matlab or C.Matlab would offer
good user friendliness but I have heard that Matlab being an interpreted
language is quite slow when it comes to loops.My requirement is about 4000
cells utmost ( 200 x 200 ) and time step of the order of 1 Pico
second.Will
Matlab be very slow that I should consider coding in C or will Matlab do
okay with respect to the execution time.



-Warm regards
--Arun S V



Don't think about it, do it. You'll find out soon enough if it's too slow.

I did one several years ago using the interpreted Visual Basic that comes
with Excel, letting Excel do the plotting. It seemed to update pretty
quickly. Matlab would probably be fine. C is great if you're comfortable
with plotting, otherwise you might spend all your time fighting the
interface. Here are some references, if you're interested:

References:



1. R. C. Booton, "Computational Methods for Electromagnetics and
Microwaves" John Wiley & Sons, Inc. 1992. This text gives an uncommonly
clear presentation of the basic theory, although it lacks enough detail to
set up practical problems of the type that we selected. The FDTD section
discusses primarily 1- and 2-dimensional problems.



2. K. S. Yee, "Numerical Solution of Initial Boundary Value Problems
Involving Maxwell's Equations in Isotropic Media," IEEE AP-14, 1966. This
is the classic paper to which all subsequent writers refer.



3. Sadiku, "Numerical Techniques in Electromagnetics." This book
provided a good level of detail for setting up FDTD problems. It provides a
good indexing scheme that makes for efficient implementation of Yee's
algorithm. This book also gives a limited discussion of absorbing boundary
conditions and briefly discusses options for feed waveforms. There is also a
brief note about reducing run times by filling the space with a low
conductivity, therefore reducing the effects of multiple reflections.



4. Omiya et. al. "Design of Cavity-Backed Slot Antennas Using the
Finite-Difference Time-Domain Technique," IEEE AP-46 Dec. 1998. This paper
provided some more detail on the problem setup, showed sensitivity of
accuracy to the number of time steps, and discussed a windowing technique
that could be used to shorten run time. It seems that this windowing in the
time domain ends up being quite similar to Sadiku's introduction of loss in
the cavity. The mathematical operations are very similar, even though the
justifications are different.



5. The Internet site "FTDT.org" has some good information and
programming examples. The content matches the information in the above
references, with more effort put into formatted output.



6. Jeong Phill Kim, "FDTD Basics and Programming Tips," March 22,
1999. This is a very clear, concise treatment of the subject with
sufficient detail to begin a practical analysis.



7. R. J. Luebbers and H. S. Langdon, "A simple feed model that
reduces time steps needed for FDTD antenna and microstrip calculations,"
IEEE AP-11, July 1996. This paper describes a feed loading technique, used
by Kim in reference 6 that greatly reduces the convergence time.



8. Cheng, Dib, and Katehi, "Theoretical Modeling of Cavity-Backed
Patch Antennas Using a Hybrid Technique. The configuration studied in this
paper is similar to the one studied in the final configuration of this
study.



9. Balanis text, "Antenna Theory Analysis and Design," 1982, Harper
and Row. There is a good description of the application of Huygen's
Principle on pages 447-456.