A Single Substrate Metasurface Dipole With Electrically Small Feeding Structure

Low-profile metasurface antennas are proposed for cellular base station applications. The dual-slant crossed-dipole antennas with four resonances employ both transverse magnetic (TM) and transverse electric (TE) surface wave modes. The metasurface dipole arms are capacitively coupled by an electrically small crossed-feed in a low-cost single substrate. The metasurface layer consists of n × n element arrays. The proposed low-profile (0.14λ ) antennas can achieve a 10-dB impedance bandwidth of 57%, 58%, and 84% for metasurface dipole arms comprising 2× 2 , 3× 3 , and 4× 4 elements, respectively. For cellular 65° sector base station applications where 14 dB is required, a bandwidth of 51%, 52%, and 63% for 2× 2 , 3× 3 , and 4× 4 elements, respectively, is realized. For a single dipole with a reflector, the average boresight gain is 9 dBi, 3-dB beamwidth is 62^° ± 7^° , front-to-back ratio is better than 25 dB, and isolation is better than 35 dB over the frequency range of 1.7-2.7 GHz. For user equipment (UE) applications, extra low-profile (0.11λ ) antennas are also presented.