Yagi-Uda Antenna on Multilayered PCB for Full-Duplex mmW Short-Range Communications

A differentially fed Yagi-Uda antenna with a folded dipole active element fabricated on a 10-layer printed circuit board (PCB) is demonstrated for 57-64 GHz short-range communications. The folded dipole arms are fabricated deep inside the PCB stack-up using the top and bottom metallization layers of the core PCB layer and connected with laser drilled microvias, allowing for a compact form factor. A multilayered PCB ground is used as the reflector and the directors are embedded into the PCB stack-up within a narrow cutout section. The proposed topology is effective in controlling the side lobe levels in order to minimize coupling between near-by antennas on the same PCB for a full-duplex multiple-input multiple-output (MIMO) operation. The reflector is placed at the top and bottom layers of the PCB, shielding the feedlines. We demonstrate that the measured impedance bandwidth of the prototype antenna covers the 55.8-66.5 GHz band and exhibits end-fire radiation that can be controlled using the width of the PCB cutout section, achieving 5.9 dB gain at 60 GHz. The small size, controllable side lobe levels and the isolated feedlines of this multilayered PCB topology makes it attractive for short-range multiple-input-multiple-output (MIMO) communications front ends.