farfield calculations (Fourier Transform)
Contents
far-field (Fraunhoffer) limit
N=1024;
D=32;
k=-N/2:N/2-1;
x = (D/N)*k;
dx = x(2)-x(1);
f = rect(x/2);
z = fftshift(fft(fftshift(f)))*dx;
fx = (1/D)*k;
fy = z.*conj(z)/4;
fprintf('maximum %g\n',max(fy));
frange=2;
idx = find(abs(fx)<frange);
subplot(1,1,1);
plot(fx(idx),fy(idx),'k','LineWidth',2);
grid;
xlabel('x/b');
ylabel('normalized irradiance');
maximum 1
Nf = 1
fslit(1);
Nf = 8
fslit(8);
compare Nf = 8
compare(8);
compare Nf = 12
compare(12);
maximum FFT extent: 1.33333
