A multiresonance metasurface antenna is proposed which has wide bandwidth and low-profile. The characteristic mode theory is used to design antenna structure. Three ideal modes are obtained by adjusting the mode currents to optimize the radiation performance of the antenna. The characteristic mode analysis is used to model, analyze, and optimize the antenna, revealing the physical characteristics of the metasurface antenna. The slot is not only used as the feeding structure for exciting characteristic modes but also introduces a slot mode. Combining the slot mode with the metasurface modes, the bandwidth of the antenna is broadened. The antenna element has a relative bandwidth of 43.7%. To obtain higher gain, a 2 × 2 antenna array is proposed. The antenna array is simulated, fabricated, and measured. The results show that the relative bandwidth of the proposed metasurface antenna array is 31.6% with the gain of 12.3–15.8 dBi over the operating bandwidth.

A multi-band circularly polarized antenna is proposed for WLAN (2.4/5.3/5.8 GHz) and WiMAX (3.5 GHz) applications. The proposed antenna is constructed of a radiation patch and a reflecting metal ground. Characteristic mode theory is utilized to analyze the modes of the patch and based on these results the antenna is optimized. The −10 dB impedance bandwidths of the proposed antenna are 53.53% (2.4–4.15 GHz) and 47.28% (5.25–8.5 GHz), respectively. The antenna radiates left-handed circular polarization in the lower band and right-handed circular polarization in the upper band. A maximum gain of 10 dBic is achieved for the proposed antenna.