Hello,
Since the type of antenna is not metioned, the pattern which is expected is unknown. So just considering the equations given and from your code, the major reason for not beig able to observe a polar plot was that equation of E had incorrect dimensions for matrix multiplication and the syntax of polarplot function was wrong. You can look into the documention here for examples on how to plot a polarplot. I have modified those lines alone and have attached the code snippet.
E = sin(Y)./(Y) .* sin(Z)./(Z); % Use .* to do elementwise multiplication
polarplot(theta,E) % phi an phino are constants
