% Figure 4.4  2-D patterns for isotropic array of N elements
% 
set(0,'defaultfigurecolor','w')
theta=0:.005:2*pi;
N=4;
   % phase shift for end-fire
%delta=-pi*sqrt(2);            % phase shift for broadside 
%delta=0;
% Array factor for d=.25;

d=.25;
delta=-2*pi*d;      % end fire
AF=sin(N*pi*d*sin(theta)+N*delta/2)./(N*pi*d*sin(theta)+N*delta/2);
figure
polarpattern(theta,abs(AF))
view(90,-90)
% Array factor for d=.5;
d=.5;
delta=-2*pi*d;      % end fire
AF=sin(N*pi*d*sin(theta)+N*delta/2)./(N*pi*d*sin(theta)+N*delta/2);
figure
polarpattern(theta,abs(AF)/max(abs(AF)))
view(90,-90)

% Array factor for d=.75;
d=.75;
delta=-2*pi*d;      % end fire
AF=sin(N*pi*d*sin(theta)+N*delta/2)./(N*pi*d*sin(theta)+N*delta/2);
figure
polarpattern(theta,abs(AF))
view(90,-90)