2-D DOA Estimation with Circular Arrays Based on the Fourth-Order Difference Co-Array

In this paper, two-dimensional (2-D) direction of arrival estimation based on the fourth-order difference co-array (FODCA) is studied. By analyzing the virtual sensor positions in FODCA, the theoretical maximum number of virtual sensors, along with the conditions under which this maximum number is achieved, have been derived. Then, a class of novel array structures, referred to as irrational partitioned circular array (IPCA), is proposed, with its provided DOFs equal to the theoretical maximum number. As demonstrated by the simulations, superior performance in terms of both the number of DOFs and estimation accuracy can be achieved by our proposed IPCA.