circular array beamforming

Dear all 
I am trying to calculate the broadband radiation pattern(beampattern) of a
circular array beamformer operating in a given frequency range(1 octave)
such that the main lobe response is approximately similar for all
frequencies i.e the beampattern is frequency invariant

I am trying to do that in MATLAB , I need help references matlab
documentation or any usefull papers 

please help 
thanks in advance