Pattern Synthesis of Unequally Spaced Linear Arrays Including Mutual Coupling Using Iterative FFT via Virtual Active Element Pattern Expansion

A virtual active element pattern (AEP) expansion method is presented in which each AEP in an unequally spaced array is considered to be the pattern radiated by a subarray of some equally spaced virtual elements. With the help of this method, the pattern of an unequally spaced array including mutual coupling can be efficiently evaluated by fast Fourier transform (FFT). By incorporating this idea into the iterative Fourier transform procedure, we develop a novel iterative synthesis method, which can apply the iterative FFT to efficiently synthesize unequally spaced arrays including mutual coupling. Different excitation constraints, such as phase-only control and amplitude-phase optimization with a prescribed dynamic range ratio, can be easily added into the proposed synthesis procedure. A set of synthesis examples for different antenna arrays with pencil and shaped beam patterns are provided to validate the effectiveness and advantages of the proposed method.