Broadband D-Band Patch Antenna Array in Wafer-Level Package Based on BCB Process

This paper presents a broadband stacked patch antenna array in wafer-level package based on benzocyclobutene (BCB) process for D-band wireless communications. The BCB material is not only used as a substrate for the antenna, but also as an interconnection layer, enabling low-loss interconnection with RFICs through vias and transmission lines. By introducing a BCB polymer-filled back cavity and carefully developing the feeding network, the designed antenna achieves a relative bandwidth of 18.9%. In addition, the
$2 \times 2$
stacked antenna array features a stable high-gain broadside radiation pattern. The pairwise antiphase feeding technique is adopted to suppress the cross-polarization level. In order to acquire high-speed data transmission, a dual-polarization MIMO implementation is presented. The port isolations are greater than 35 dB across the whole operating band.