Beam scanning of a phased array antenna

Beijing Institute of Technology | Ming-Jian Li

The following MATLAB code is a companion code for the course on Artificial Intelligence and Simulation Science. It functions to calculate the beam scanning process of a phased array antenna.

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clear;clc;
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freq=300e6;   omega=2*pi*freq;  c=3e8; 
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lambda=c/freq;    k=2*pi/lambda;   
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d=lambda*0.5;  
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M=6
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N=6
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R=(M+1)*d/2;    f=1*R*2;
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xm=-R+d:d:R-d;  yn=-R+d:d:R-d;
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[x y]=meshgrid(xm,yn);
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rf=[0 0 f];  u0hat=[0 0 1];
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qe=1;
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theta=linspace(0,pi/2,200);phi=linspace(0,pi*2,200);  
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[THETA,PHI]=meshgrid(theta,phi);   
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nImages = 24; 
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fig = figure;
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thetabeam=-pi/6;
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phibeam=0;
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for idx=1:nImages
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    if idx<nImages/2
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        thetabeam=thetabeam+pi/6*4/nImages;
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    else
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        thetabeam=thetabeam-pi/6*4/nImages;
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    end
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    % phibeam=phibeam+2*pi/nImages;
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    E_total=zeros(200,200);  
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    for im = 1:M
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        for in = 1:N
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            rmn=[x(im,in) y(im,in) 0];
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            rm_rf=rmn-rf;
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            mag_rmn_rf=norm(rm_rf,2);
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            phimn(im,in)=k*(mag_rmn_rf ...
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            -(x(im,in)*cos(phibeam)+y(im,in)*sin(phibeam))*sin(thetabeam) );
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            reflect_amp(im,in)=1;
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            E_total=E_total+reflect_amp(im,in).*exp(1i.*(phimn(im,in)+k.*d.*((in-1/2).*cos(PHI)+(im-1/2).*sin(PHI)).*sin(THETA))); 
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        end
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    end
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    Ex=abs(E_total).*sin(THETA).*cos(PHI);
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    Ey=abs(E_total).*sin(THETA).*sin(PHI);
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    Ez=abs(E_total).*cos(THETA);  
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    set(gcf,'Position',[100 100 640 480]) 
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    surf(Ex,Ey,Ez,'EdgeColor','none');  
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    shading interp
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    colormap jet
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    axis([-20 20 -20 20 0 40]);
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    drawnow
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    frame = getframe(fig); 
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    img{idx}=frame2im(frame);
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end
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timedelay=0.2;
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filename = 'scan.gif';  
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for idx = 1:nImages
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    [A,map] = rgb2ind(img{idx},256);
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    if idx == 1
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        imwrite(A,map,filename,'gif','LoopCount',Inf,'DelayTime',timedelay);
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    else
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        imwrite(A,map,filename,'gif','WriteMode','append','DelayTime',timedelay);
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    end
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end

The result is as follows.