plotting complex exponential function
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f=(0:10000);
d=(0.0075:0.03);
w=2*pi*f;
t=(0:0.2);
k=(81.6*pi);
rin=0.71;
%x=rin*exp(-1i*2*k*d);
y=0.71*exp(-1i*2*k*d);
d=abs(y);
plot(real(d),imag(y));
xlabel("thickness",'fontsize',10);
ylabel("rin",'FontSize', 10);
title("Input reflection coefficient as a function of the physical thickness 𝜆 ⁄ 8≤ 𝑑 ≤ 𝜆⁄2 ","fontsize",6);
grid on;
here is my code but when i try to run it it work but i dont gate any sygnal on de graphe the graph are just empty
i dont understant it please some one can help me or explain at the place i dit a wrong code
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Answers (2)
Walter Roberson
on 20 Jan 2023
d=(0.0075:0.03);
w=2*pi*f;
t=(0:0.2);
The default increment for the : operator is 1, so you are programming
d=(0.0075:1:0.03);
w=2*pi*f;
t=(0:1:0.2);
but 0.0075+1 > 0.03 so d will only have a single entry, and 0+1 > 0.2 so t will only have a single entry.
Walter Roberson
on 20 Jan 2023
Removing the variables that you do not use, and setting a finer increment for d
d=(0.0075:0.001:0.03);
k=(81.6*pi);
y=0.71*exp(-1i*2*k*d);
plot(real(y),imag(y));
xlabel("thickness",'fontsize',10);
ylabel("rin",'FontSize', 10);
title("Input reflection coefficient as a function of the physical thickness 𝜆 ⁄ 8≤ 𝑑 ≤ 𝜆⁄2 ","fontsize",6);
grid on;
You were taking real(abs(y)) as your independent coordinate, but real(abs(y)) is constant
syms D
Y=0.71*exp(-1i*2*k*D);
abs(Y)
but D is real so imag(D) is 0, so abs(Y) is the constant 71/100
2 Comments
Walter Roberson
on 20 Jan 2023
t=(0:0.1);
That means you want to construct the list of numbers that starts with 0, and increases by 1 each time, and ends no later than 0.1 . That list describes only a single number.
Your f values are all integers and 2*pi*integer is a full sine or cosine cycle, so *exp(-1i*w*t) will have 0 imaginary part anywhere that t is an integer. But there is only 1 t value and it is an integer, so imag(y) is going to be 0 at that one location.
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