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matlab script of the gaussian excitation of openEMS

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Sebastian Held 2010-04-21 18:04:50 +02:00
parent f356ff105c
commit ab13b34404
1 changed files with 37 additions and 0 deletions
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matlab/examples/gauss_excitation_test.m Normal file
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clear
close all
f0 = 1e9/2;
fc = 1e9/2;
dT = 8e-12; % sample time-step
len = 2 * 9/(2*pi*fc) / dT; % gauss length
for n=1:len
ex(n)=cos(2*pi*f0*((n-1)*dT - 9/(2*pi*fc))) .* exp(-1*(2*pi*fc*(n-1)*dT/3-3).^2);
t_(n)=(n-1)*dT;
end
plot(t_/1e-9,ex)
xlabel( 'time (ns)' );
ylabel( 'amplitude' );
disp( ['Amplitude at t=0: ' num2str(20*log10(abs(ex(1))/1)) ' dB'] );
val = DFT_time2freq( t_, ex, [f0-fc f0 f0+fc] );
disp( ['Amplitude at f=f0-fc: ' num2str(20*log10(abs(val(1))/abs(val(2)))) ' dB'] );
disp( ['Amplitude at f=f0+fc: ' num2str(20*log10(abs(val(3))/abs(val(2)))) ' dB'] );
freq = linspace(f0-fc,f0+fc,1000);
val = DFT_time2freq( t_, ex, freq );
figure
plot( freq/1e9, abs(val) )
[f,val] = FFT_time2freq( t_, ex );
val = val((f0-fc<=f) & (f<=f0+fc));
f = f((f0-fc<=f) & (f<=f0+fc));
hold on
plot( f/1e9, abs(val), 'r' )
xlabel( 'frequency (GHz)' );
ylabel( 'amplitude' );