Via-Fed Active Microstrip Antenna Using Multi-Layer Ceramic-Polyimide Substrates

This paper proposes a three-dimensional active antenna configuration for the front-end module of a high-speed wireless communication system using millimeter and quasi-millimeter-wave frequencies. The three-dimensional structure enables unrestricted RF-circuit design on multi-layer polyimide and yields good characteristics although via cover pads are required to form the via-fed microstrip antennas (MSA). This is confirmed by analyses and experiments conducted at 18.5 GHz. The results indicate that the optimum slot width between the via cover pads and the ground plane lies between 300 ¿ and 400 ¿m. Moreover, setting the slot width to 300 ¿m improves cross polarization.