Phase error analysis of a dual polarized concentric ring array

Abstract : In a previous work a dual-polarized non-uniform concentric ring array of spirals has been developed. This array used the sequential rotation technique as a means to enhance the array's axial ratio and the non-uniform concentric rings to reduce the relative side lobe level. In the present paper the effects of realizing the phases of the sequential rotation using digital phase shifters are analyzed, considering both the phase-quantization and the phase-error effects in the broadside radiation of the array. We show that by considering a 2-bit phase shifter with a centered Gaussian error (sigma=5°) in each element of the array the axial ratio is kept under 1dB over the whole bandwidth, with a maximal degradation of 0.85dB when compared with the array without phase-errors or phase-quantization. We also show that the side lobe level suffers a maximal degradation of 4dB for the 2-bit phase shifter, however it is not affected by the phase error.