Metasurface Based Performance Enhancement of Circularly Polarized Antenna for MIMO Communication Applications

This paper presents an effective method to improve performance of circularly polarized (CP) microstrip patch MIMO antenna. Basically, when two CP patches are positioned close to each other, narrow band operation and poor isolation are achieved. For performance enhancement, metasurface (MS) is employed. The useful of MS in increasing operating bandwidth and isolation as well has been demonstrated by two different designs. In the one hand, position MS unit cells surround the radiating patches can improve the bandwidth to 10.5% (5.0-5.55 GHz) and the isolation of better than 20 dB with element spacing of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.08\lambda$</tex>. On the other hand, placing a proper number of MS unit cells over the radiating elements can achieve higher bandwidth of 16.2% (5.1-6.0 GHz) and isolation of greater than 25 dB with element spacing of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.022\lambda$</tex>.