Millimeter Wave Wideband and Wide Scanning Angle Circular-Polarized Sip-Based Antenna Array

This paper presents a Millimeter wave wideband and wide scanning angle circular-polarized System-in-Package (Sip)-based antenna array. Multiple layers of Printed Circuit Board (PCB) are used for lamination, integrating the beamforming network and feeding network onto the same PCB board. Surface-Laminar-Circuit (SLC) organic packaging substrate technology is low-cost with vertical interconnections made through vias to support flip chips and applied for the Sip integration with antennas. The antenna elements use corner truncated square patch structures to achieve circular polarization radiation. Sequential rotation feeding is employed to significantly enhance circular polarization radiation performance. Due to limitations of PCB integration with Sip-based chips, the Sip integration with PCB antennas only support a 4-element sub-array. A large phased array consists of planar well-aligned sub-arrays, which suffers physical metal ground discontinuity between each sub-array, and induces in-band common-mode resonance. Slotted via cavities between antenna elements are utilized to reduce coupling, suppress common-mode resonances, and further solve the ground discontinuity issue. The array operates within a bandwidth of 24 GHz to 28 GHz (15%) and supports scanning angles of ±60°. Within the scanning range of ±60°, the axial ratio is less than 3.6 dB, and the gain degradation is about 4.7 dB.