Reduction of Main Beam-Blockage in an Integrated 5G Array With a Metal-Frame Antenna

In this paper, a novel technique is introduced to reduce the handset metal-frame blockage to the main beam of a millimeter-wave (mm-wave) endfire antenna array. The metal-frame blockage to mm-wave antennas with different polarizations is investigated first. It is found that the blockage is more severe for horizontal polarization than for vertical polarization. The effect of the metal bezel on an mm-wave array with horizontal polarization can be significantly decreased if two-tilted layers of coupled metal strips are placed at the borders of the frame. Furthermore, these metal strips are shown not to disturb the mm-wave antennas with vertical polarization. Different detailed design considerations are studied. To further demonstrate the idea, a 5G Vivaldi array (with horizontal polarization) is designed and integrated with a metal frame. The frame functions as a low-frequency antenna, operating in two frequency bands of 865-990 and 1358-2786 MHz. The mm-wave array with four elements operates at the frequency band 24.25-27.5 GHz and can scan ±60° in endfire direction, with a realized gain higher than 7 dBi in most of the frequency range.