Highly Unidirectional Slot Antenna Using Transmissive and Reflective Metasurfaces for WLAN and WiMAX Applications

To achieve highly unidirectional radiation in a conventional microstrip-fed slot antenna, two different special metasurfaces were designed and used. The first metasurface with transmissive characteristic is placed in front of the antenna for radiation enhancement on forward direction. Then, the second metasurface with reflective feature is located behind the slot antenna to suppress back lobe emission. By properly aligning antenna among two metasurfaces, the proposed antenna achieves good impedance bandwidth for WLAN (2.40-2.484 GHz) and WiMAX (2.50-2.69 GHz) applications. Moreover, the antenna can provide high level of front-to-back-ratio (FTBR) as 25.03 and 20.08 at the operating frequencies of 2.45 and 2.60 GHz, respectively.