Dipole antenna far-field pattern

I need to plot the radiation pattern for a dipole antenna of length L=lambda/2. The example plot given was of L=1.4*lambda.

Example plot of L=1.4*lambda:

My code to try and reproduce the plot for L=1.4*lambda:

 %Wavelength
lam = 1;
%Dipole antanna
L = 1.4*lam;
%Phase constant
B = 2*pi/lam;
t = 0:0.01:2*pi;
% Far-field pattern equation    
E = abs((cos(B*L/2*cos(t))-cos(B*L/2))./sin(t));
figure()
polar(t,E)

Plot from this code:

I can't figure out where I'm going wrong with this one...

[neil whitesell]

is ther i version of this with a current input???

Answer 1

[David Goodmanson]

Hi Vinci, power is proportional to the square of the electric field, so if you use

E2 = abs((cos(B*L/2*cos(t))-cos(B*L/2))./sin(t)).^2;
figure()
polar(t,E2)

the correct figure should pop up.

[Vinci]

Yep, that was it. Perfect!

Answer 2

[Omkar Savkur]

Hi Vinci, building off David's answer, you can use the polarpattern function to help plot the radiation power. You can interact with the plot and specify the plot parameters all in one line.

% Wavelength
lam = 1;
% Dipole antanna
L = 1.4*lam;
% Phase constant
B = 2*pi/lam;
% Angle in degrees
t = 0:0.1:360;
% Far-field pattern equation 
E = abs((cos(B*L/2*cosd(t))-cos(B*L/2))./sind(t)).^2;
figure(1)
polarpattern(t,E,'AngleResolution',30)

You can also use other Antenna Toolbox functions, like pattern, which plots far-field radiation patterns. EHfields can be used to plot electric and magnetic fields at any observation locations, both near and far-field components.