Matlab-Codes.rar_jammer _matlab jammer_radar jammer_radar jammer

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Written for Course :- Computational Electromagnetics, Fall 2011 % Department of Electrical Engineering % Indian Institute of Technology Madras % Chennai - 600036, India % % Authors :- Sathya Swaroop Ganta, B.Tech., M.Tech. Electrical Engg. % Kayatri, M.S. Engineering Design % Pankaj, M.S. Electrical Engg. % Sumanthra Chaudhuri, M.S. Electrical Engg. % Projesh Basu, M.S. Electrical Engg. % Nikhil Kumar CS, M.S. Electrical Engg. % % Instructor :- Ananth Krishnan % Assistant Professor % Department of Electrical Engineering % Indian Institute of Technology Madras % % Any correspondance regarding this program may be addressed to % Prof. Ananth Krishnan at '[email protected]' % % Copyright/Licensing :- For educational and research purposes only. No % part of this program may be used for any financial benefit of any kind % without the consent of the instructor of the course. % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % "2D FDTD solution for Perfectly Matched Layer (PML) boundary condition" % % Objective of the program is to solve for the Maxwell's equation for a TM % wave containing the xy-plane polarized magnetic field having components Hy % and Hx and z-polarized electric field Ez. The fields are updated at every % timestep, in a space, where all physical parameters of free space are not % normalized to 1 but are given real and known values. The update is done % using standard update equations obtained from the difference form of Maxwell's % curl equations with very low electric and magnetic conductivities of 4x10^(-4) % units incorporated in them. The field points are defined in a grid described % by Yee's algorithm. The H fields are defined at every half coordinate of % spacesteps. More precisely, the Hx part is defined at every half y-coordinate % and full x-coordinate and the Hy part is defined at every half x-coordinate % and full y-coordinate and E fields i.e the Ez part is defined at every full % x and full y-coordinate points.Also here, the space-step length is taken % as 1 micron instead of 1 unit in unitless domain assumed in previous programs. % Also, the time update is done using Leapfrog time-stepping. Here, H-fields % i.e. Hx and Hy are updated every half time-step and E fields i.e Ez are % updated every full time-step. This is shown by two alternating matrix updates % spanning only a part of spatial grid where the wave, starting from source, % has reached at that particular time instant avoiding field updates at all % points in the grid which is unnecessary at that time instant. These spatial % updates are inside the main for-loop for time update, spanning the entire % time grid. Also, here, the matrices used as multiplication factors for update % equations are initialized before the loop starts to avoid repeated calculation % of the same in every loop iteration, a minor attempt at optimization. The % boundary condition here is Perfectly Matched Layer (PML) boundary condition % where the fields near the boundary are attenuated over a predetermined length % of boundary width before they reach the boudary to a zero value at the boundary % using a polynomially increasing electrical conductivity value over the boundary % width with maximum at the boundary and also chosing a magnetic conductivity % value at every point in the boundary width to avoid reflection at that % point given in [1]. Also, here, Berenger's PML condition is used where in % the field Ez is split into two components Ezx and Ezy and the components % are attenuated using separate electric and magnetic conductivities in the % two directions (sigmax and sigma_starx in x direction and sigmay and sigma_stary % in the y direction). % % A source of electric field is defined at the center of the spatial domain, % which is a hard source, in that it does not change its value due to % interference from external fields i.e in other words, the source is a % perfect electric conductor. The form of the source can be varied using % the variables sine, gaussian and impulse. The source is available in four % standard forms- Unit-time step, Impulse, Gausian and Sinusoidal forms. % The color scaled plot of Ez field over the entire spatial domain is shown % at every time step. The simulation can be ended by closing this plot window % or by waiting till all the time step updates are completed. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %Clearing variables in memory and Matlab command screen clear all; clc; % Grid Dimension in x (xdim) and y (ydim) directions xdim=200; ydim=200; %Total no of time steps time_tot=350; %Position of the source (center of the domain) xsource=100; ysource=100; %Courant stability factor S=1/(2^0.5); % Parameters of free space (permittivity and permeability and speed of % light) are all not 1 and are given real values epsilon0=(1/(36*pi))*1e-9; mu0=4*pi*1e-7; c=3e+8; % Spatial grid step length (spatial grid step= 1 micron and can be changed) delta=1e-6; % Temporal grid step obtained using Courant condition deltat=S*delta/c; % Initialization of field matrices Ez=zeros(xdim,ydim); Ezx=zeros(xdim,ydim); Ezy=zeros(xdim,ydim); Hy=zeros(xdim,ydim); Hx=zeros(xdim,ydim); % Initialization of permittivity and permeability matrices epsilon=epsilon0*ones(xdim,ydim); mu=mu0*ones(xdim,ydim); % Initializing electric conductivity matrices in x and y directions sigmax=zeros(xdim,ydim); sigmay=zeros(xdim,ydim); %Perfectly matched layer boundary design %Reference:-http://dougneubauer.com/wp-content/uploads/wdata/yee2dpml1/yee2d_c.txt %(An adaptation of 2-D FDTD TE code of Dr. Susan Hagness) %Boundary width of PML in all directions bound_width=25; %Order of polynomial on which sigma is modeled gradingorder=6; %Required reflection co-efficient refl_coeff=1e-6; %Polynomial model for sigma sigmamax=(-log10(refl_coeff)*(gradingorder+1)*epsilon0*c)/(2*bound_width*delta); boundfact1=((epsilon(xdim/2,bound_width)/epsilon0)*sigmamax)/((bound_width^gradingorder)*(gradingorder+1)); boundfact2=((epsilon(xdim/2,ydim-bound_width)/epsilon0)*sigmamax)/((bound_width^gradingorder)*(gradingorder+1)); boundfact3=((epsilon(bound_width,ydim/2)/epsilon0)*sigmamax)/((bound_width^gradingorder)*(gradingorder+1)); boundfact4=((epsilon(xdim-bound_width,ydim/2)/epsilon0)*sigmamax)/((bound_width^gradingorder)*(gradingorder+1)); x=0:1:bound_width; for i=1:1:xdim sigmax(i,bound_width+1:-1:1)=boundfact1*((x+0.5*ones(1,bound_width+1)).^(gradingorder+1)-(x-0.5*[0 ones(1,bound_width)]).^(gradingorder+1)); sigmax(i,ydim-bound_width:1:ydim)=boundfact2*((x+0.5*ones(1,bound_width+1)).^(gradingorder+1)-(x-0.5*[0 ones(1,bound_width)]).^(gradingorder+1)); end for i=1:1:ydim sigmay(bound_width+1:-1:1,i)=boundfact3*((x+0.5*ones(1,bound_width+1)).^(gradingorder+1)-(x-0.5*[0 ones(1,bound_width)]).^(gradingorder+1))'; sigmay(xdim-bound_width:1:xdim,i)=boundfact4*((x+0.5*ones(1,bound_width+1)).^(gradingorder+1)-(x-0.5*[0 ones(1,bound_width)]).^(gradingorder+1))'; end %Magnetic conductivity matrix obtained by Perfectly Matched Layer condition %This is also split into x and y directions in Berenger's model sigma_starx=(sigmax.*mu)./epsilon; sigma_stary=(sigmay.*mu)./epsilon; %Choice of nature of source gaussian=0; sine=0; % The user can give a frequency of his choice for sinusoidal (if sine=1 above) waves in Hz frequency=1.5e+13; impulse=0; %Choose any one as 1 and rest as 0. Default (when all are 0): Unit time step %Multi