Multiple Beam Synthesis of Passively Cooled 5G Planar Arrays Using Convex Optimization

An extended-feature, system-driven convex algorithm for the synthesis of uniform-amplitude, irregular planar phased arrays with simultaneous multi-beam optimization for mm-wave 5G base station applications in multi-user scenarios is presented. The inter-user interferences are suppressed by minimizing the maximum sidelobe level (SLL) for a beam scanned freely inside a given sector. The aperture size is restricted to the size of the heatsink baseplate dimensions. A minimum guaranteed inter-element spacing in the final layout is pre-defined, which prevents element overlapping, eases the thermal problem and helps reduce the effects of high mutual coupling (MC). The algorithm performance is tested via the synthesis of a 64-element integrated array with at least half a wavelength inter-element spacing. The optimized array results show that, compared to their regular counterparts, significant reduction in the SLLs is achieved for a beam scanned inside the defined sector, while keeping the maximum temperature of the array at a reliable level. The effect of MC on the results is also investigated via full-wave simulations and it is explained how embedded element patterns can potentially be included in the optimization. Superior capabilities of the proposed method are illustrated by comparing the algorithm output to those reported in the state-of-the-art literature.