A ±45° Dual-Polarized Dual-Beam Series-Fed Metasurface Antenna Array With Stable Beam Angle

A novel method to realize positive phase response of antenna element is proposed conceptually and applied in ±45° dual-polarized dual-beam series-fed metasurface antennas (MSAs). It takes the features of stable beam angle within the relative bandwidth of 10% and dual-polarized dual beams. Benefiting from the positive phase response zone of the antenna, the long-line effect is eliminated and the phase response between the elements is reshaped as expected. Therefore, a stable beam of series-fed array oriented at specific angle is guaranteed accordingly. To achieve the ±45° dual-polarized dual-beam performance, a four-port MSA element with interwoven feeding network is designed and used for further array design. For demonstration, one prototype of MSA array is designed. Considering the band of 4.7–5.2 GHz (10%), the beam angle of the MSAs based on positive phase response control (PPRC) method is oriented to 30°, and the variation versus frequency is less than 6°, which is smaller than the variation of 19° for traditional array. The simulation and measurement results show that stable beam angle is achieved for the dual-polarized series-fed MSA array, indicating a promising candidate for base-station application.