A Broadband Co-Linearly Polarized Full-Duplex Antenna-in-Package (AiP) for Integrated Sensing and Communication

A novel 24 GHz ISM-band broadband co-linearly polarized full-duplex microstrip antenna-in-package (AiP) with high isolation and wide isolation bandwidth is proposed for integrated sensing and communication (ISAC) in this paper. Two $\mathbf{1}\times \mathbf{2}$ microstrip patch antenna arrays are used as Tx and Rx antennas, respectively. The direction of the feeding ports is orthogonal to that of the elements to improve the Tx/Rx isolation. In addition, parasitic patches are introduced to enlarge the impedance bandwidth of the proposed AiP. To further suppress surface waves and space waves between array elements, two decoupling loops with different optimized lengths are employed to enhance Tx/Rx isolation and widen isolation bandwidth. The simulation results demonstrate that the proposed AiP possesses the merits of wide impedance bandwidth (up to 10% from 22.5 to 24.9 GHz), high Tx/Rx isolation (up to 52 dB), and wide isolation bandwidth (greater than 40 dB across 22.9-24.87 GHz). The measured data show good agreement with simulated results, further proving the feasibility of this design methodology.