Robust beamforming in circular arrays using phase-mode transformation

Having many benefits, phase-mode transformation technique is used frequently in beamforming with circular arrays. Owig to the fact that this transformation is frequency dependent, some techniques are used to make this transformation appropriate for broadband applications. When this technique is used with uniform circular arrays, its performance degrades because of the approximations applied to the formulations. In this study, the authors propose a new beamforming method not only robust against uncertainty in the steering vector of the desired signal, but also robust against errors caused by the phase-mode transformation. The authors assume that steering vector of the desired signal pertains to a ball set and ellipsoid sets are considered to cover the transformation matrix columns. The proposed beamforming method is based on semi-definite programming. The performance of the proposed beamforming method is compared with several other beamforming techniques by using a simulation study.