Sparse Linear Arrays of Vector Antennas for Fourth-Order Direction Finding

Sparse linear arrays such as nested arrays, coprime arrays, and minimum redundancy arrays (of omnidirectional or vector antennas) have reduced inter-antenna mutual coupling as compared to the uniform linear arrays. However, there still exist at least one antenna pair in these arrays whose spacing is less than or equal to the half of signal wavelength. To reduce further the inter-antenna mutual coupling, a new sparse linear array of vector antennas (VAs) has been designed in the context of fourth-order (FO) cumulant based direction finding of statistically independent narrowband non-Gaussian signals. The minimum inter-VA spacing of the array is constrained to be no less than one signal wavelength while synthesizing a virtual linear VA array with maximum contiguous aperture. The FO direction finding scheme for the designed array has also been presented. The effectiveness of the designed array in reducing inter-VA mutual coupling and achieving unambiguous FO direction finding is validated by using both simulated and real-world data.