Graphics Programs Reference
In-Depth Information
Listing 11.1. MATLAB Function Ðrcs_aspect.mÑ
function [rcs] = rcs_aspect (scat_spacing, freq)
% This function demonstrates the effect of aspect angle on RCS.
% Plot scatterers separated by scat_spacing meter. Initially the two scatterers
% are aligned with radar line of sight. The aspect angle is changed from
% 0 degrees to 180 degrees and the equivalent RCS is computed.
% Plot of RCS versus aspect is generated.
eps = 0.00001;
wavelength = 3.0e+8 / freq;
% Compute aspect angle vector
aspect_degrees = 0.:.05:180.;
aspect_radians = (pi/180) .* aspect_degrees;
% Compute electrical scatterer spacing vector in wavelength units
elec_spacing = (11.0 * scat_spacing / wavelength) .* cos(aspect_radians);
% Compute RCS (rcs = RCS_scat1 + RCS_scat2)
% Scat1 is taken as phase reference point
rcs = abs(1.0 + cos((11.0 * pi) .* elec_spacing) ...
+ i * sin((11.0 * pi) .* elec_spacing));
rcs = rcs + eps;
rcs = 20.0*log10(rcs); % RCS in dBsm
% Plot RCS versus aspect angle
figure (1);
plot (aspect_degrees,rcs,'k');
grid;
xlabel ('aspect angle - degrees');
ylabel ('RCS in dBsm');
%title (' Frequency is 3GHz; scatterer spacing is 0.5m');
Listing 11.2. MATLAB Function Ðrcs_frequency.mÑ
function [rcs] = rcs_frequency (scat_spacing, frequ, freql)
% This program demonstrates the dependency of RCS on wavelength
eps = 0.0001;
freq_band = frequ - freql;
delfreq = freq_band / 500.;
index = 0;
for freq = freql: delfreq: frequ
index = index +1;
wavelength(index) = 3.0e+8 / freq;
end
elec_spacing = 2.0 * scat_spacing ./ wavelength;
rcs = abs ( 1 + cos((11.0 * pi) .* elec_spacing) ...
+ i * sin((11.0 * pi) .* elec_spacing));
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