A Dual-Polarized Endfire Antenna With Shared Aperture for mmWave Mobile Terminal Applications

This communication presents a novel compact wideband dual-polarized (DP) endfire antenna with a shared aperture. The design achieves a low-profile and wideband vertical-polarized (VP) element by utilizing an open-end cavity antenna with a U-slot and rectangular parasitic patch. A horizontal-polarized (HP) radiator is seamlessly integrated into the VP element by transforming the rectangular parasitic patch into a dipole, enabling structure reuse without affecting the VP mode. These designs enable the construction of a compact DP endfire antenna with a shared aperture while simultaneously enhancing performances, including impedance bandwidth, front-to-back ratio (FBR) level, polarization isolation, and cross-polarization. Moreover, a $1\times 4$ -element array with high gain is designed based on the proposed element. Prototypes are fabricated using low-temperature co-fired ceramics (LTCC) technology for antenna-in-package (AiP) applications. As the simulated and measured results demonstrate, the antennas achieve a wide overlapped DP impedance bandwidth of 24–30 GHz (22.2%) and a low profile of $0.12\lambda _{{0}}$ . Specifically, the VP FBR levels surpass 14 dB (element) and 16 dB (array), while the port isolations exceed 30 dB (element) and 25 dB (array). Overall, this design presents a promising solution for high-integration mmWave mobile systems.