A single fed wideband mode-reconfigurable OAM metasurface CP antenna array with simple feeding scheme

In this paper, a low-profile mode reconfigurable orbital angular momentum (OAM) circular polarization (CP) array antenna is presented, which consists of 2 x 2 elements and a single feed network. Each element is a metasurface subarray composed of 4 x 4 square patchs. The vias in the subarray produces 90 degrees phase difference between x- and y- polarizations, and CP is realized. Both the 90 degrees phase-shifting reconfigurable feed network and broadband 180 degrees phase shift by the mirror images are used to generate the OAM helical phase. The OAM modes l can be dynamically switched between l = +1 and l = -1 by controlling operation states of p-i-n diodes in the feed network. The CP and OAM impedance bandwidths are 13.3% (from 5.8 to 6.6 GHz). The peak gains for the two modes are 9.4 dBi. The developed array antenna has the following advantages of the least pin diode number, high gain, small size, lowest divergence angle, wideband CP, low cross-polarization and low fabrication cost. Therefore, the proposed antenna is very promising for modern high-speed and large capacity wireless communication systems.