Gain And Side Lobe Level Enhancement Of Array Antennas Using Metasurface Superstrates

This paper presents a wide-band circularly polarized antenna, and a systematic procedure for designing antenna arrays comprising of crossed-bowtie (cloverleaf) radiating elements. We show gain improvements ranging from 6.87dB for a single element to 15.84dB for 3x3 and to 20.5dB for 5x5 with Side Lobe Level (SLL)-12.8dB and -11.5dB. The Metasurface Superstrate (MSS) further improves the gain to 18.6dB for 3x3 and 22.4dB for 5x5 and SLL to -20.9dB and -14.7dB. The optimum height for the MSS superstrate is lambda/4 to realize the best gain and SLL performance. The realized return loss (S-11) bandwidth of the single antenna element is 38.5%, and its 3dB axial ratio (AR) bandwidth is 41.5 %. The proposed antenna arrays may be useful for C-band satellite communication.