Extensions of Open Box Array With Reduced Mutual Coupling

Mutual coupling effect and degree of freedom are two important factors to be considered in the planar sparse array (PSA) design. This paper presents two new planar sparse geometries, referred to as the half H array and ladder array, by introducing the effective difference co-array concept and redistributing the dense array elements of the open box array (OBA) to the outer diagonal straight line. The detection capacities of the new structures can be maintained at the same level as the OBAs. Furthermore, they possess much fewer sensor pairs closely spaced, leading to the mutual coupling between the adjacent sensors significantly reduced. Simulations of the direction-of-arrival estimation verify the superiorities of the proposed PSAs with the 2-D unitary ESPRIT algorithm.