Polarization-Reconfigurable Enhanced Ellipse-Shaped Metasurfaces Antenna With Integrated Filtering Functions

This letter proposes a tri-polarization reconfigurable diversity antenna with integrated filtering functions based on ellipse-shaped metasurfaces (MTS). The antenna consists of three layers: the feedline layer, the coupled aperture layer, and the MTS layer. To get a low-frequency radiation null, the complementary split ring resonators (CSRRs) are loaded on the coupled aperture layer, utilizing resonant characteristics. Furthermore, a nonradiation characteristics mode of the MTS is excited for a high-frequency radiation null. Thus, a filtering function of the proposed antenna is provided. Besides, there are three coupled slots on the aperture layer. Six sets of PIN diodes are inserted on the microstrip and coupled aperture. Through controlling the PIN diode, the polarization reconfigurability is obtained by choosing different coupled slots and changing the associated electric field vector. Eventually, the proposed antenna could switch between linear polarization (LP), left-hand circular polarization (LHCP), and right-hand circular polarization. In the experiment, the proposed antenna shows a wide -10 dB impedance bandwidth (IMBW) of 29% and 29.5% for LP and CP modes. While operating in CP modes, the antenna has a wide measured 3 dB axial ratio (AR) bandwidth of 29%. Meanwhile, the out-of-band radiation suppression level in low frequency is more than 30 dB and 20 dB for LP and CP modes, respectively.