A circular-polarization high-efficiency wide-angle-AR four-beam AiP phased array for commercial aerospace communication

This paper proposes an 8 $\times$ 8-element circularly polarized (CP) four-beam receiving (Rx) antenna-in-packaging (AiP) phased array for commercial aerospace communication (CAC) to achieve high total radiation efficiency (TRE) and wide-scanning axial ratio (AR) at the same time. The phased array is divided into 16 AiP modules, one of which consists of the 2 $\times$ 2-element subarray and a four-element four-beam Rx GaAs beamforming integrated circuit (BFIC). The designed three-dimension (3-D) stacked BFIC shows an excellent performance with a compact size. The high TRE is realized with the dielectric-free radiation element and the 3-D interconnection. The L-shape structure is reused support pillar and the feeding structure. The modification for the 8 $\times$ 8-element AiP subarray solves the problem that it is difficult to realize a good CP of the phased array with the single-port feeding. The prototype of the AiP phased array is manufactured. The measured results demonstrate that the AR is below 5 dB within the scanning range of $\pm60^\circ$. The $G/T$ and TRE are $-$4.8 dB/K and 82% at 29 GHz, respectively.