Adaptive Beamforming with a Double-Cross Array of Dipoles on a Drone

Adaptive and reconfigurable beamforming from an array of vertical half-wavelength dipole elements on a drone is considered. The array consists of nine dipole radiators that are located on a “double-cross” layout consisting of a central element that is surrounded by eight adjacent neighboring dipoles. The double-cross layout dimensions are optimized beforehand. The amplitudes and phases of the nine dipole radiators are then used as degrees of freedom and are optimized to give specified far-field patterns. The desired patterns may have one or more main beams, together with one or more nulls and low sidelobes. A fast relaxation method is proposed to optimize the associated nonlinear (and non-convex) cost functional and obtain the complex dipole currents (magnitudes and phases). A simple iterative approach that does not require an optimizer is also proposed. Dynamic null steering is also examined, in which the current of the central array element is adjusted dynamically to steer a null on the fly.