format short
%create some data that has the required characteristics
N = complex(rand(4,60), rand(4,60));
for K = 1 : 60; c = randperm(4,2); N(c,K) = conj(N(c,K)); end
%now process
Matrix1 = N(sub2ind(size(N), sum(cumprod(imag(N) < 0))+1, 1:size(N,2)));
Matrix2 = N(sub2ind(size(N), sum(cumprod(imag(N) > 0))+1, 1:size(N,2)));
%and check.
disp(N(:,1:3))
disp(Matrix1(1:3))
disp(Matrix2(1:3))
%the below is not relevant to the code you wanted. I happened to notice a display bug
%so I am using the below as part of a report to Mathworks.
N(:,1:4)
N(:,1:5)
N(1:10)