Electronic Countermeasures (ECM) - MATLAB Simulations for Radar Systems Design - page 492

soj(index) = s_at_br - s_at_br;
end
ranvar = .1:1:1000;
%ranvar = ranvar ./BR_range;
semilogx (ranvar,s,'k',ranvar,soj,'k-.');
xlabel ('Range normalized to cross-over range');
legend('Target echo','SOJ')
ylabel ('Relative signal or jamming amplitude - dB');
Listing 10.5. MATLAB Function Ðrange_red_factor.mÑ
function RRF = range_red_factor (te, pj, gj, g, freq, bj, rangej, lossj)
% This function computes the range reduction factor and produces
% plots of RRF versus wavelength, radar to jammer range, and jammer power
c = 3.0e+8;
k = 1.38e-23;
lambda = c / freq;
gj_10 = 10^( gj/10);
g_10 = 10^( g/10);
lossj_10 = 10^(lossj/10);
index = 0;
for wavelength = .01:.001:1
index = index +1;
jamer_temp = (pj * gj_10 * g_10 *wavelength^2) / ...
(4.0^2 * pi^2 * k * bj * lossj_10 * (rangej * 1000.0)^2);
delta = 10.0 * log10(1.0 + (jamer_temp / te));
rrf(index) = 10^(-delta /40.0);
end
w = 0.01:.001:1;
figure (1)
semilogx(w,rrf,'k')
grid
xlabel ('Wavelength in meters')
ylabel ('Range reduction factor')
index = 0;
for ran =rangej*.3:1:rangej*2
index = index + 1;
jamer_temp = (pj * gj_10 * g_10 *wavelength^2) / ...
(4.0^2 * pi^2 * k * bj * lossj_10 * (ran * 1000.0)^2);
delta = 10.0 * log10(1.0 + (jamer_temp / te));
rrf1(index) = 10^(-delta /40.0);
end
figure(2)
ranvar = rangej*.3:1:rangej*2 ;