Low-Profile 5G mmWave Antenna-in-Package with Dual-Polarization Operation

A compact 5G mmWave antenna-in-package (AiP) with a low-profile 5-layered substrate is proposed in this conference paper. A very thin liquid crystal polymer (LCP) substrate topology is utilized with an overall thickness of 0.5 mm (around $0.05\lambda_{\mathbf{0}}$ at 28 GHz) only. The proposed antenna is dual-polarized and with a shorted patch radiator and a magnetic dipole radiator, which respectively contribute to the horizontal polarization (H-pol) and the vertical polarization (V-pol). For H-pol, the shorted patch radiator is excited by aperture coupled feeding via dual slots present in the ground plane. Additionally, two resonant $TM_{1/2,0,0}^{z}$ and $TM_{1,0,0}^{z}$ modes are excited in the patch that aids in the wideband coverage. For V-pol, the microstrip magnetic dipole radiator is fed by the coaxial feedline and loaded with a reflector behind the dipole to improve the front-to-back ratio. Both the orthogonal antenna ports cover the n257 5G mmWave frequency band (26.5-29.5 GHz). An optimal peak gain of more than 7.5 dBi is achieved for both antenna ports.