Radar Cross Section (RCS) - MATLAB Simulations for Radar Systems Design - page 561

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--','line-
width',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;
Listing 11.7. MATLAB Function Ðrcs_circ_plate.mÑ
function [rcsdb] = rcs_circ_plate (r, freq)
% This program calculates and plots the backscattered RCS of
% circular flat plate of radius r.
eps = 0.000001;
% Compute aspect angle vector
% Compute wavelength
lambda = 3.e+8 / freq; % X-Band
index = 0;
for aspect_deg = 0.:.1:180
index = index +1;
aspect = (pi /180.) * aspect_deg;
% Compute RCS using Eq. (2.37)
if (aspect == 0 | aspect == pi)
rcs_po(index) = (4.0 * pi^3 * r^4 / lambda^2) + eps;
rcs_mu(index) = rcs_po(1);
else
x = (4. * pi * r / lambda) * sin(aspect);
val1 = 4. * pi^3 * r^4 / lambda^2;
val2 = 2. * besselj(1,x) / x;
rcs_po(index) = val1 * (val2 * cos(aspect))^2 + eps;
% Compute RCS using Eq. (2.36)
val1m = lambda * r;