www.pudn.com > programradarsystemdisign.zip > fig11_18a.m

% Use this program to reproduce Fig. 11.18a 
%This program computes the back-scattered RCS for an ellipsoid. 
% The angle phi is fixed to three values 0, 45, and 90 degrees 
% The angle theta is varied from 0-180 deg. 
% A plot of RCS versus theta is generated 
% Last modified on July 16, 2003 
clear all; 
 
% ===   Input parameters   === 
a = .15;            % 15 cm 
b = .20;            % 20 cm 
c = .95 ;           % 95 cm 
% ===   End of Input parameters   === 
 
as = num2str(a); 
bs = num2str(b); 
cs = num2str(c); 
eps = 0.00001; 
dtr = pi/180; 
for q = 1:3 
    if q == 1  
        phir = 0;       % the first value of the angle phi 
    elseif q == 2 
        phir = pi/4;    % the second value of the angle phi 
    elseif q == 3 
        phir = pi/2;    % the third value of the angle phi 
    end    
    sin_phi_s = sin(phir)^2; 
    cos_phi_s = cos(phir)^2; 
    % Generate aspect angle vector 
    theta = 0.:.05:180; 
    thetar = theta * dtr; 
    if(a ~= b & a ~= c) 
        rcs(q,:) = (pi * a^2 * b^2 * c^2) ./ (a^2 * cos_phi_s .* (sin(thetar).^2) + ... 
            b^2 * sin_phi_s .* (sin(thetar).^2) + ... 
            c^2 .* (cos(thetar).^2)).^2 ; 
    elseif(a == b & a ~= c) 
        rcs(q,:) = (pi * b^4 * c^2) ./ ( b^2 .* (sin(thetar).^2) + ... 
            c^2 .* (cos(thetar).^2)).^2 ; 
    elseif (a == b & a ==c) 
        rcs(q,:) = pi * c^2; 
    end 
end 
rcs_db = 10.0 * log10(rcs); 
figure (1); 
plot(theta,rcs_db(1,:),'b',theta,rcs_db(2,:),'r:',theta,rcs_db(3,:),'g--','linewidth',1.5); 
xlabel ('Aspect angle, Theta [Degrees]'); 
ylabel ('RCS - dBsm'); 
title (['Ellipsoid with (a,b,c) = (', [as],', ', [bs],', ', [cs], ')  meter']) 
legend ('phi = 0^o','phi = 45^o','phi = 90^o') 
grid;