A Dual-Broadband Dual-Polarized Patch Antenna Array Antenna-in-Package (AiP) Module on Asymmetric Substrate Stack-up

This study presents a broadband, dual-polarized stacked patch antenna array module developed for mobile Antenna-in-Package (AiP) applications utilizing an asymmetric substrate stack-up. A key design challenge in 5G mmWave AiP systems is achieving wideband operation, dual-polarization, and compact form factor simultaneously-particularly under the spatial constraints of mobile devices. To address this, the proposed antenna incorporates an L-probe feeding, which significantly enhances impedance bandwidth through capacitive coupling and broadband matching. Built on a 14-layer asymmetric substrate with a total thickness of 1, $205 \; \mu $ m, the antenna achieves dual-band impedance bandwidths of $24.2\sim 30.9$ GHz and $35.8\sim 41.9$ GHz, effectively covering all 5G mmWave bands from n258 to n261. The antenna demonstrates low envelope correlation and high polarization isolation, essential for massive MIMO implementations. Integrated with RFICs, the AiP module achieves measured gains of 10.2 dBi and 11.1 dBi at 28 GHz and 39 GHz, respectively, within a compact form factor of $5.9 \times 23 \times 2.1$ mm ${}^{\mathbf {3}}$ ( $0.48 \; \lambda _{\mathbf {0}} \times 1.86 \; \lambda _{\mathbf {0}} \times 0.17 \; \lambda _{\mathbf {0}}$ ). The active module supports beam-steering up to ±45° and achieves EIRP values of 29.5 dBm at both frequency bands. It is also compatible with high-order modulation schemes (up to 256-QAM), maintaining an EVM below 4.5%. This work provides a practical and scalable AiP solution, addressing the key design constraints of next-generation mmWave mobile devices.