fig13_12a.m
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上传日期:2020-09-25
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- % Use this program to reproduce Fig. 13.12aa
- %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;