LTCC-based Dual-Polarized AiP Module by Multilayered Cross-Dipole Antennas for 5G Mobile Terminal Applications at 28 GHz Band

An antenna-in-package (AiP) of 4 × 4 elements with dual-polarized radiations for high-power radiation at a 28 GHz band was designed and fabricated by low-temperature co-fired ceramic (LTCC) for 5G applications. The design starts with selecting cross-dipole elements to ensure good polarization purity. The l/4 separation from a ground plane is achieved by considering a proper combination of multilayered substrates' thicknesses and their dielectric constant, where the feedings are probed by coaxial-type vias from the bottom. The dipole arms' shapes are optimally tuned to achieve broadband reflection coefficients. This AiP has the advantage of dual-polarizations along +/-45 degrees to avoid harmful interferences from metal-supporting structures, reasonable inter port isolations, and low cross-polarization levels. The AiP has a compact profile of 28x28 mm 2 . The inter-port isolation between the polarization excitation ports is larger than 33dB from HFSS full-wave simulations. The elements' bandwidth is larger than 6 GHz from the full-wave simulation and broader than 4 GHz from measurements over the antenna prototype. The array has a bandwidth larger than 6 GHz from measurement with a maximum gain of 16.6dBi and a sidelobe level of 13.3 dB, validating the design concept.