Dielectric Cylinder 2D

中文/English

Dielectric cylinder 2D TM (Ex Ez Hy)


The FonSinEM simulation results V.S. Analytical solution


2D (TM) dielectric cylinder(Y-axis infinity) - To simulate the scattering-absorption spectrum in optical range

The radius of cylinder is 200 nm (diameter = 400 nm), and the refractive index n=1.5. permittivity = n^2=2.25



Add the boundary of the CAD files (FreeCAD)



Due to FreeCAD default unit is mm, and in this case the sphere unit is nm. If use nm unit in FreeCAD, the resolution of output STL file will not enough. So, at here express

"the unit can directly transform between any unit, nm <=> um <=> mm "


FreeCAD:


diameter of cylinder: 0.4 mm = 400 um

length of the boundary: 1 mm = 1000 um


Define Parameters

1. Selected the simulation dimension.

2. Define total x, y, z length that equal to CAD, and then set a appropriate resolution.

3. Import CAD files.

4. Define the material of each CAD.

5. Press【建立網格 Cad to Grids (Create)】button to create simulation grids.


* Dielectric Constant of cylinder define n^2 = 1.5^2 = 2.25,




(FreeCAD : um ==> FonSinEM : nm )


FreeCAD

diameter of cylinder: 0.4 mm = 400 um

length of the boundary: 1 mm = 1000 um


FonSinEM

Attention! the X, Z length define 1000, unit is nm

and the cylinder will be 400 nm in FonSinEM

"the unit can directly transform between any unit, nm <=> um <=> mm "



A. Define the boundary conditions

B. Press the【創建 (Create)】button => Create the total grid size (Include the boundary condition & add space)




To simulate the Scattering-Absorption spectrum, select the (TFSF-RCS) radar cross section source


Checked out the simulation geometries, and then press 【輸出 Output】button to output the geometries files

Data_Materials.csv // (simulation index of structures)




1. Set the Spectrum Analysis & Wavelength range

2. Check out the source



1. Set the simulation time setp

2. Save parameters

3. Calculation


★(Result Analysis):

頻譜 (Spectrum) : Analysis the spectrum



Comparison of FonSinEM simulation results and analytical solution


Mie theory software


MieLab:

A Software Tool to Perform Calculations on the Scattering of Electromagnetic Waves by Multilayered Spheres
http://www.hindawi.com/journals/ijs/2011/583743/
 
 

Nmie:


This website contains many freeware,FDTD、FEM、Ray tracing method and mie theory codes

http://www.scattport.org/diogenes.iwt.uni-bremen.de/vt/scattport/index.php/light-scattering-software/mie-type-codes.html



====== Far-Field Diffraction Pattern Analysis=====

The near to far field transformation (NTFF) is a technology that to integrate the near field EM wave to the far-field diffraction pattern in FDTD algorithm. In FonSinEM, can use the "Pulse" and "Continue Wave (CW)" to do this. The difference between these is


In Pulse source, the observation range are fixed, but can obtain multi frequencies far field pattern at once calculation.

Menu ==> 【其它 Other】==>【遠場Far-Field】


In CW source, the frequency is fixed, but can change observation range arbitrary.

Use the steady state filed pattern analysis




following are the detail of these two NTFF method.



================== (Pulse) ================



1. Checked "Pulse" wave

2. Checked ☑近場觀測輸出 (Output NearField Ob.)-脈波 (Pulse Only)


The observation range will be defined automatically if the incident source type is TFSF-RCS.


after calculation finished, will output

Pulse_DFT_1_p1.csv

Pulse_DFT_2_p1.csv

these two files, these are the EM data of the near field simulation.




3. Menu : 其他(Other) ==> 遠場 (Far Field)


Source type : TFSF-RCS*

Source type : Others


Output the far-field values of the FonSinEM simulation

use the following code


csvwrite('scan_theta.csv',scan_theta)
csvwrite('RCS_theta.csv',RCS_theta)
csvwrite('RCS_phi.csv',RCS_phi)



The analytical solution code

MatScat
Author :Jan Schäfer

http://www.mathworks.com/matlabcentral/fileexchange/36831-matscat


scan_theta=csvread('scan_theta.csv');
RCS_theta=csvread('RCS_theta.csv');
RCS_phi=csvread('RCS_phi.csv');
 
%% Define test parameters
lambda0=400e-9;
dia = 400e-9;       % cylinder diameter
ns = 1.5 + 0.j;     % cylinder refractive index (complex)  epsr=ns^2
nm = 1;             % outer medium refractive index (real)
nang = 180;         % number of far field angles to evaluate
zeta = 90;          % cylinder inclination angle (90 deg = perpendicular)
[T, C, ang] = calccyl(dia/2., ns, nm, lambda0, nang, zeta);
fctr = 2/pi/C.k;
Far2E= fctr*squeeze(abs(T(2,2,:).^2));    % 2E
figure(1);hold on;
plot(scan_theta,RCS_theta(172,:),'r','Linewidth',3);
plot(ang, Far2E/max(Far2E(:))*max(RCS_theta(172,:)),'*b');
xlabel('Scattering Angle');
title('TM(ExEzHy)')
legend('FDTD','Analytical Solution')



Comparison of FonSinEM and Analytical solution









================== (CW) ================

Here choice the wavelength (lambda)=400 nm source of CW wave



Steady state field pattern analysis


Setup the observation range and then press the (NTFF Transformation) button

observation range : x=19,213, z=19,213 . In field pattern analysis, can change the observation range arbitrary



Output the far-field values of the FonSinEM simulation

use the following code


a(:,1)=scan_theta';
a(:,2)=RCS_theta';
a(:,3)=RCS_phi';
csvwrite('Far2DTM.csv',a)




The analytical solution code


MatScat
Author :Jan Schäfer

http://www.mathworks.com/matlabcentral/fileexchange/36831-matscat



load Far2DTM.csv
scan_theta=Far2DTM(:,1);
RCS_theta=Far2DTM(:,2);
RCS_phi=Far2DTM(:,3);
lambda0=400e-9;
%% Define test parameters
dia = 400e-9;  % cylinder diameter
ns = 1.5 + 0.j;     % cylinder refractive index (complex)  epsr=ns^2
nm = 1;         % outer medium refractive index (real)
nang = 180;         % number of far field angles to evaluate
zeta = 90;         % cylinder inclination angle (90 deg = perpendicular)
[T, C, ang] = calccyl(dia/2., ns, nm, lambda0, nang, zeta);
fctr = 2/pi/C.k;
Far2E= fctr*squeeze(abs(T(2,2,:).^2));    % 2E
figure(1);hold on;
plot(scan_theta,RCS_theta,'r','Linewidth',3);
plot(ang, Far2E/max(Far2E(:))*max(RCS_theta(:)),'*b');
xlabel('Scattering Angle');
title('TM(ExEzHy)')
legend('FDTD','Analytical Solution')



Comparison of FonSinEM and Analytical solution



Mie theory software


MieLab:

A Software Tool to Perform Calculations on the Scattering of Electromagnetic Waves by Multilayered Spheres
http://www.hindawi.com/journals/ijs/2011/583743/
 
 

Nmie:


This website contains many freeware,FDTD、FEM、Ray tracing method and mie theory codes

http://www.scattport.org/diogenes.iwt.uni-bremen.de/vt/scattport/index.php/light-scattering-software/mie-type-codes.html