Modeling and Design of Microstrip Patch Antenna-in-Package for Integrating the RFIC in the Inner Cavity

This letter presents the circuit model of the antenna-in-package (AiP) for integrating the RFIC in the inner cavity. The closed-form expression for the inductance of the ground via is provided in the case that two ground vias are arranged under the nonradiating edge of the AiP. The new expression takes account of the radius and length of the vias, the relative positions of vias, and the distances between via holes and the feeding point of the antenna. Based on the circuit model, the influences of vias on the performance of the AiP are analyzed. It is found that the bandwidth of the AiP can be effectively improved by properly arranging two via holes under the nonradiating edge of the antenna. Finally, an AiP with the center frequency of 5.12 GHz is realized, and a bandwidth of 400 MHz is obtained. The calculated results are in agreement with the simulated and measured.