rcs_rect_plate.m
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上传日期:2020-09-25
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- function [rcsdb_h,rcsdb_v] = rcs_rect_plate(a, b, freq)
- % This program computes the backscattered RCS for a rectangular
- % flat plate. The RCS is computed for vertical and horizontal
- % polarization based on Eq.s(13.52)through (13.62). Also Physical
- % Optics approximation Eq.(13.64) is computed.
- % User may vary frequency, or the plate's dimensions.
- % Default values are a=b=10.16cm; lambda=3.25cm.
- eps = 0.000001;
- % Enter a, b, and lambda
- lambda = .0325;
- ka = 2. * pi * a / lambda;
- % Compute aspect angle vector
- theta_deg = 0.05:0.1:85;
- theta = (pi/180.) .* theta_deg;
- sigma1v = cos(ka .*sin(theta)) - i .* sin(ka .*sin(theta)) ./ sin(theta);
- sigma2v = exp(i * ka - (pi /4)) / (sqrt(2 * pi) *(ka)^1.5);
- sigma3v = (1. + sin(theta)) .* exp(-i * ka .* sin(theta)) ./ ...
- (1. - sin(theta)).^2;
- sigma4v = (1. - sin(theta)) .* exp(i * ka .* sin(theta)) ./ ...
- (1. + sin(theta)).^2;
- sigma5v = 1. - (exp(i * 2. * ka - (pi / 2)) / (8. * pi * (ka)^3));
- sigma1h = cos(ka .*sin(theta)) + i .* sin(ka .*sin(theta)) ./ sin(theta);
- sigma2h = 4. * exp(i * ka * (pi / 4.)) / (sqrt(2 * pi * ka));
- sigma3h = exp(-i * ka .* sin(theta)) ./ (1. - sin(theta));
- sigma4h = exp(i * ka * sin(theta)) ./ (1. + sin(theta));
- sigma5h = 1. - (exp(j * 2. * ka + (pi / 4.)) / 2. * pi * ka);
- % Compute vertical polarization RCS
- rcs_v = (b^2 / pi) .* (abs(sigma1v - sigma2v .*((1. ./ cos(theta)) ...
- + .25 .* sigma2v .* (sigma3v + sigma4v)) .* (sigma5v).^-1)).^2 + eps;
- % compute horizontal polarization RCS
- rcs_h = (b^2 / pi) .* (abs(sigma1h - sigma2h .*((1. ./ cos(theta)) ...
- - .25 .* sigma2h .* (sigma3h + sigma4h)) .* (sigma5h).^-1)).^2 + eps;
- % Compute RCS from Physical Optics, Eq.(2.62)
- angle = ka .* sin(theta);
- rcs_po = (4. * pi* a^2 * b^2 / lambda^2 ).* (cos(theta)).^2 .* ...
- ((sin(angle) ./ angle).^2) + eps;
- rcsdb_v = 10. .*log10(rcs_v);
- rcsdb_h = 10. .*log10(rcs_h);
- rcsdb_po = 10. .*log10(rcs_po);
- figure(2)
- plot (theta_deg, rcsdb_v,'k',theta_deg,rcsdb_po,'k -.','linewidth',1);
- set(gca,'xtick',[10:10:85]);
- freqGH = num2str(freq*1.e-9);
- A = num2str(a);
- B = num2str(b);
- title (['Vertical Polarization, ','Frequency = ',[freqGH],' GHz, ', ' a = ', [A], ' m',' b = ',[B],' m']);
- ylabel ('RCS -dBsm');
- xlabel ('Aspect angle - deg');
- legend('Eq.(13.52)','Eq.(13.63)')
- figure(3)
- plot (theta_deg, rcsdb_h,'k',theta_deg,rcsdb_po,'k -.','linewidth',1);
- set(gca,'xtick',[10:10:85]);
- title (['Horizontal Polarization, ','Frequency = ',[freqGH],' GHz, ', ' a = ', [A], ' m',' b = ',[B],' m']);
- ylabel ('RCS -dBsm');
- xlabel ('Aspect angle - deg');
- legend('Eq.(13.53)','Eq.(13.63)')