Design of Tri-Polarized Bandwidth-Enhanced Metasurface Antenna Using Characteristic Mode

A tri-polarized bandwidth-enhanced metasurface antenna is presented for the 5G indoor access point application. First, a feeding pin with a coupling disk introduces a new omnidirectional mode at the lower band. Second, two via groups are added to control the two omnidirectional modes. Subsequently, four slots are etched on the middle four patches to adjust the two degenerate broadside modes and lower the resonant frequency of a pair of high-order broadside modes. Finally, the six operation modes of the metasurface were tuned to design a tri-polarized metasurface antenna with over 27dB of isolation in the 3.3-4.2GHz range. The measured gains of the broadside and omnidirectional ports are greater than 6.6 and 4.3 dBi, respectively. The proposed metasurface antenna has significant potential for indoor 5G access point applications.