Surface and Volume Clutter - MATLAB Simulations for Radar Systems Design - page 286

SLv = 10.0^(SL/10); % radar rms sidelobes in volts
sigma0v = 10.0^(sigma0/10); % clutter backscatter coefficient
tau = 1/b; % pulsewidth
deltar = clight * tau / 2.; % range resolution for unmodulated pulse
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
range_m = 1000 .* range; % range in meters
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
thetar = asin(hr ./ range_m);
thetae = asin((ht-hr) ./ range_m);
propag_atten = 1. + ((range_m ./ rh).^4); % propagation attenuation due to
round earth
Rg = range_m .* cos(thetar);
deltaRg = deltar .* cos(thetar);
theta_sum = thetae + thetar;
% use sinc^2 antenna pattern when ant_id=1
% use Gaussian antenna pattern when ant_id=2
if(ant_id ==1) % use sinc^2 antenna pattern
ant_arg = (2.78 * theta_sum ) ./ (pi*thetaE);
gain = (sinc(ant_arg)).^2;
else
gain = exp(-2.776 .*(theta_sum./thetaE).^2);
end
% compute sigmac
sigmac = (sigma0v .* Rg .* deltaRg) .* (pi * SLv * SLv + thetaA .* gain.^2) ./
propag_atten;
sigmaC = 10*log10(sigmac);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
if (size(range,2)==1)
fprintf('Sigma_Clutter='); sigmaC
else
figure(1)
plot(range, sigmaC)
grid
xlabel('Slant Range in Km')
ylabel('Clutter RCS in dBsm')
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Calculate CNR
pt = pt * 1000;
g = 26000 / (thetaA_deg*thetaE_deg); % antenna gain
F = 10.^(f/10); % noise figure is 6 dB
Lt = 10.^(l/10); % total radar losses 13 dB
k = 1.38e-23; % BoltzmanÓs constant
T0 = t0; % noise temperature 290K