Wideband 45° Linearly Polarized Slot Array Antenna Based on Gap Waveguide Technology for 5G Millimeter-Wave Applications

This letter presents a wideband high performance 45° linearly polarization 8 × 8-slot array antenna. The gap waveguide technology is utilized to realize the proposed antenna, so that the electromagnetic (EM) leakage among the metallic blocks can be cancelled. 2 × 4-slot subarrays are used to construct the array antenna. An additional cavity power divider layer is inserted between the layers of original cavity power dividers and radiation slots to balance the amplitude and phase distributions in wideband frequency band. This suppresses the grating lobes. Triangular blocks are loaded in the new cavity power divider layer to confine the EM field distribution, thereby improving cross-polarization discrimination (XPD). For demonstration, a prototype antenna covering 5G millimeter-wave (mmW) NR bands of 257, 258, and 261 is design, fabricated, and measured. Measured results show that an impedance bandwidth of 23-30 GHz (|S
₁₁
|<; -10.5 dB) is achieved. Within this frequency band, the peak gain and antenna efficiency are more than 24.6 dBi and 76.3%. In addition, the sidelobe level (SLL) of lower than -25.8 dB and XPD of better than 30.2 dB are also obtained over the same frequency band.