Lengthened Coprime Arrays With Hole-Free Coarrays and Reduced Mutual Coupling

This paper presents hole-free lengthened coprime arrays with reduced mutual coupling (rLCAs). Based on the k-times extended coprime array structure, the rLCAs are designed by positioning two sparse subarrays outside the original aperture. An enhanced rLCA is further derived via locating and rearranging an inessential sensor. This enhanced rLCA is able to increase the number of degrees of freedom (DOFs). Compared with other arrays, the proposed rLCAs exhibit more DOFs and significantly reduced mutual coupling. The achievable DOFs of the rLCAs are derived and analyzed in detail. Finally, numerical examples show that the proposed rLCAs provide reduced mutual coupling and higher estimation accuracy.