Phased Arrays - MATLAB Simulations for Radar Systems Design - page 380

%
%%%% Element expression needs to be modified if different
%%%% than a short dipole antenna along the z axis
clear all
clf
% close all
% ==== Input Parameters ====
a = 1.; % radius of the circle
N = 20; % number of Elements of the circular array
theta0 = 45; % main beam Theta direction
phi0 = 60; % main beam Phi direction
% Theta or Phi variations for the calculations of the far field pattern
Variations = 'Phi'; % Correct selections are 'Theta' or 'Phi'
phid = 60; % constant phi plane for theta variations
thetad = 45; % constant theta plane for phi variations
% ==== End of Input parameters section ====
dtr = pi/180; % conversion factors
rtd = 180/pi;
phi0r = phi0*dtr;
theta0r = theta0*dtr;
lambda = 1;
k = 2*pi/lambda;
ka = k*a; % Wavenumber times the radius
jka = j*ka;
I(1:N) = 1; % Elements excitation Amplitude and Phase
alpha(1:N) =0;
for n = 1:N % Element positions Uniformly distributed along the circle
phin(n) = 2*pi*n/N;
end
switch Variations
case 'Theta'
phir = phid*dtr; % Pattern in a constant Phi plane
i = 0;
for theta = 0.001:1:181
i = i+1;
thetar(i) = theta*dtr;
angled(i) = theta; angler(i) = thetar(i);
Arrayfactor(i) = 0;
for n = 1:N
Arrayfactor(i) = Arrayfactor(i) + I(n)*exp(j*alpha(n)) ...
* exp( jka*(sin(thetar(i))*cos(phir -phin(n))) ...
-jka*(sin(theta0r )*cos(phi0r-phin(n))) );
end
Arrayfactor(i) = abs(Arrayfactor(i));