Compact Dual-Band Shared-Aperture Base-Station Antenna Array Using Transparent Wideband Absorbing Metasurface and Radiator-Reused Scheme

This paper presents a novel dual-band shared-aperture antenna array with ±45° dual polarization for 4G/5G base stations. The proposed array is composed of a lower-band (LB) magneto-electric (ME) dipole antenna, 4 higher-band (HB) dipole antennas and a transparent absorbing metasurface. Each radiator of the proposed LB ME dipole antenna is designed into a square cavity, and HB antennas are embedded into the cavities. Based on the radiator-reused scheme, the total size of the array is reduced by about 26%. A novel wideband absorbing metasurface made of transparent material of Indium Tin Oxide is completed. The proposed metasurface can absorb the HB electromagnetic wave radiated by HB induced current on the LB antenna, reflect the LB electromagnetic wave, and reduce the out-of-band gain of the LB antenna by about 3 dB. By fully using the proposed metasurface, the cross-band isolation between LB and HB elements is easily increased by over 10 dB. Distortion of the HB antenna radiation pattern is also mitigated. The simulated and measured results demonstrate that the proposed array can cover wider bandwidths of 0.67-0.98 GHz (37.6%) and 3.17-5.2 GHz (48.5%), and has higher cross-band isolation of over 30 dB than previous works.