%Minimum variance Array Weights
%  example 8.5
d=.5;
N= 5;
sig2=.001;        % noise variance
theta=-pi/2:.01:pi/2;
ang=theta*180/pi;
th0=30*pi/180;      % receive angle
th1=-10*pi/180;
s=1;                %signal amplitude

a=[];
n1=[];
n2=[];
n=-(N-1)/2:(N-1)/2;
a=exp(1j*2*pi*n*d*sin(th0));  % array steering vector
n1=exp(1j*2*pi*n*d*sin(th1));  % array steering vector
a=a.';
n1=n1.';
Rss=a*a.';              % signal correlation matrix  
Rii=n1*n1';             % interferer 1 correlation matrix  
Rnn=sig2*eye(N);        % noise correlation matrix       
Ruu=Rii+Rnn;            % total undesired signal correlation matrix
w=inv(Ruu)*a./(a'*inv(Ruu)*a);           % calculated weight vector

for j=1:length(theta)
    th=theta(j);
    aa=[exp(1j*2*pi*n*d*sin(th))]; 
    aa=aa.';
    y(j)=w'*aa;
end
figure;
plot(ang,abs(y)/max(abs(y)),'k')
axis([-90 90 0 1])
xlabel('\theta')
ylabel('|AF(\theta)|')
num2str(a,2)