Wide-Angle Scanning Design of Irregular Arrays Based on Unequal Phase Feeding

The widespread application of irregular arrays is prevented due to their low gain and high sidelobe at large scanning angles. This article proposes a wide-angle scanning approach based on unequal phase feeding for irregular arrays. Through different phase feeding for elements in a subarray, the radiation vector is deflected, reducing the relative wavelength path distance. The proposed array realizes improved directivity and low sidelobes at large scanning angles, at the cost of a small reduction of directivity in the broadside. The method of symmetrical phase exchange achieves wideband capability, even though the unequal phase delay is frequency-dependent. A mixed-integer linear programming model is proposed for the design of irregular subarray partitioning and phase distribution. Simulation results show that the scanning range can be further extended from +/- 35 degrees to +/- 65 degrees compared with the state-of-the-art method. To demonstrate the feasibility of the proposed method, a prototype including an antenna array and divider networks is fabricated and measured. Measured results show that the realized gain (RG) of the proposed array exceeds that of the state-of-the-art array by about 4.0 dB at large scanning angles, at the cost of a 1.9 dB reduction in broadside gain at the highest frequency.