# field distribution using 3D FDTD

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#### ravi8331

##### Full Member level 4
Hii
i want to calculate electric field distribution within a dielectric slab due to direct contact with an antenna using 3D FDTD .
plz tell me how can i calculate the electric field distribution using 3D FDTD.
i want to see the varriation of electric field with x, y and z direction within the dielectric slab.
plz help me.
i want to do this using MATLAB.
plz help me .....................
if anyone have any example or any document related to this problem then plz mail me at ravi8331@gmail.com

Two good books - "The Finite-Difference Time-Domain Method for Electromagnetics with Matlab Simulations" by Elsherbeni and Demir and "Electromagnetic Simulation Using the FDTD Method" by Sullivan. I don't think that either have complete code, but they can get you there. You could also try looking through the archives, here, because I think people occasionally post FDTD sample code.

i have both books and i hv gone through these books and in first book author provide information about field distribution in 2D but not in 3D and similarly in second book will not provide any thing for 3D object.
i want to do in 3D objects..if anybody having anything which can help me then plz send me......................or upload here.............
thanks ................

• mimokoko

### mimokoko

Points: 2
i have both books and i hv gone through these books and in first book author provide information about field distribution in 2D but not in 3D and similarly in second book will not provide any thing for 3D object.

That is because there is no conceptual difference.

As far as code is concerned:
2d => double loop
3d => triple loop

ok here i will provide the code in 2D then plz do the modiofication and convert it in to 3D..
% display sampled electric fields on a plane
for ind=1:number_of_sampled_transient_E_planes
figure(sampled_transient_E_planes(ind).figure);
Es = zeros(nxp1, nyp1);
component = sampled_transient_E_planes(ind).component;
switch (component)
case 'x'
Es(2:nx,: ) = 0.5 * (Ex(1:nx-1,: ) + Ex(2:nx,: ));
case 'y'
Es ,2:ny) = 0.5 * (Ey ,1:ny-1) + Ey ,2:ny));
case 'z'
Es = Ez;
case 'm'
Exs(2:nx,: ) = 0.5 * (Ex(1:nx-1,: ) + Ex(2:nx,: ));
Eys ,2:ny) = 0.5 * (Ey ,1:ny-1) + Ey ,2:ny));
Ezs = Ez;
Es = sqrt(Exs.^2 + Eys.^2 + Ezs.^2);
end
imagesc(xcoor,ycoor,Es.');
axis equal; axis xy; colorbar;
title(['Electric field <' component '>[' num2str(ind) ']']);
drawnow;
end

% capture sampled time harmonic electric fields on a plane
for ind=1:number_of_sampled_frequency_E_planes
w = 2 * pi * sampled_frequency_E_planes(ind).frequency;
Es = zeros(nxp1, nyp1);
component = sampled_frequency_E_planes(ind).component;
switch (component)
case 'x'
Es(2:nx,: ) = 0.5 * (Ex(1:nx-1,: ) + Ex(2:nx,: ));
case 'y'
Es( :,2:ny) = 0.5 * (Ey( :,1:ny-1) + Ey( :,2:ny));
case 'z'
Es = Ez;
case 'm'
Exs(2:nx,: ) = 0.5 * (Ex(1:nx-1,: ) + Ex(2:nx,: ));
Eys( :,2:ny) = 0.5 * (Ey ( :,1:ny-1) + Ey( :,2:ny));
Ezs = Ez;
Es = sqrt(Exs.^2 + Eys.^2 + Ezs.^2);
end
sampled_frequency_E_planes(ind).sampled_field = ...
sampled_frequency_E_planes(ind).sampled_field ...
+ dt * Es * exp(-j*w*dt*time_step);
end

plz tell me the correction to covert it into 3D electric field distribution..............

ok here i will provide the code in 2D then plz do the modiofication and convert it in to 3D..

Sorry, I do not touch matlab (or whatever that is).
There also are a number of unexplained function calls.

plz help me i m still waiting for ur response................................

Dear ravi8331

Do you have the ebook of 'The Finite-Difference Time-Domain Method for Electromagnetics with Matlab Simulations'. If you have, will you please send it to me. My Email is nmliuhai@163.com

Is there any good book that is explaining everything from basic?

See Allen Taflove's book.

The name is Computational Electrodynamics: The Finite-Difference Time-Domain Method. You can find it in www dot 4shared dot com

Good morning everybody:

I've been working on a program that analyzes microstrip antennas usig FDTD with MATLAB, unfortunately my code doesn't work well yet. Maybe if you see this code you can solve some of your questions. This implementation was made in MATLAB using a vectorization method to reduce the proccesing time.

If someone has the book "The Finite Difference Time Domain Method for Electromagnetics: With MATLAB Simulations", Atef Elsherbeni and Veysel Demir
can you send it to me please, I really need that book. My email is floydsteven77@gmail.com

maxwell.j.c said:
See Allen Taflove's book.

The name is Computational Electrodynamics: The Finite-Difference Time-Domain Method. You can find it in www dot 4shared dot com

Hi. I cant seem to find it. Could you kindly advise?

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