Design of a sparse antenna array for radar‐based structural health monitoring of wind turbine blades

The imaging performance of a sparse antenna array depends on the arrangement of the transmitting and receiving elements. In this study, the authors systematically extend the work presented by Caba and Boreman by a constraint optimisation of the Y‐shaped antenna arrangement. This will lead to an improved point‐spread function with reduced sidelobes. It was found that a 30% improvement of the imaging performance using backprojection techniques could be achieved compared with conventional array designs. The optimised sparse antenna array has been used in a simulation study to evaluate its performance for radar‐based structural health monitoring of wind turbine blades. Depending on the damage position, either close to the front or back side of the rotor blade, the localisation error has been quantified as a function of its generally unknown effective relative permittivity.