60 GHz Compact Multidirectional, Multibeam Antenna-in-Package

In this study, a multidirectional, multibeam antenna-in-package (AiP) was proposed for the 60 GHz unlicensed band (57–66 GHz). The vertically polarized endfire horn antenna and broadside horn antennas were arranged and integrated into a single substrate with a
$1\times4$
array structure to cover all the radial axes. In contrast to previous horn-type AiP structures, a guard via was added to suppress back radiation. In addition, impedance matching vias and impedance matching patches were analyzed in detail to widen the impedance bandwidth. The guard via was also analyzed. An efficient AiP was designed by minimizing the overlapped beamwidth of the antenna radiating in broadside and endfire directions; this was possible because the E- and H-plane beamwidths, respectively, can be adjusted by controlling the horn aperture. Each beamforming function of the broadside and endfire array was realized by integrating each radio frequency integrated circuit (RFIC) to the corresponding array. The size of the antenna was
$7.5\times 10.6\times1.51$
mm (
$= 1.5\times 2.12\times 0.302\,\,\lambda _{0}^{3}$
). The proposed
$1\times4$
array AiP had 8.5 and 9.1 dBi realized gains for the endfire and broadside horns, respectively, and the measured
$S_{11}$
covered 57–66 GHz. Therefore, the proposed antenna is expected to be mounted and used in mobile devices, such as virtual reality (VR), head-mounted displays (HMDs), and augmented reality (AR) glasses.