A Shared-Aperture Cavity Slot Antenna-in-Package Concept Featuring End-Fire and Broadside Radiation for Enhanced Beam Coverage of mmWave Mobile Devices

A shared-aperture cavity slot antenna (SACSA) is proposed and demonstrated at millimeter-wave spectrum for the first time. The endfire and broadside antennas can independently operate within an identical cavity, thus sharing a common aperture. The endfire antenna is implemented as an open-ended cavity slot antenna (CSA) topology featuring $+y$ -axis directional beam, and broadside antenna is realized as a cavity backed slot antenna featuring +z-axis directional beam. For reducing a mutual coupling between endfire and broadside antennas, two antennas are designed to feature orthogonal polarization of each other. The reflection coefficients of two antennas satisfy less than −10 dB at operating frequency band while maintaining mutual coupling coefficient under −25 dB. The realized gain of 1 $\times $ 4 SACSA is approximately 9.56 dBi for endfire antenna and 8.9 dBi for broadside antenna, and 3 dB scanning angle of both antennas is ± 45° at respective dominant directions. Accordingly, the proposed SACSA can be implemented as a compact size of antenna-in-package (AiP) by sharing the aperture of two antennas and enhancing beamforming coverage by independently steering two separate beams.