Broadband Circularly Polarized Antenna Based on Multi-layer PCB technology for Millimeter-Wave Applications

A broadband circularly-polarization antenna unit and array working at millimeter wave band (21-28GHz) for millimeter wave applications is proposed. This antenna has promising feeding structures of 4-L probes to realize the good performance of broadband and circularization. The 4x4 antenna array with the $\theta.5 \lambda$ distance of units is present. This proposed antenna array has great wide bandwidth of 28% and high isolation better than 20dB. This antenna unit and array can be realized based on the multi-layer PCB technology. The measurement results by experience show good agreement with the simulation. Therefore, these antenna unit and array that have great electrical performance and process feasibility that can be used for the 5G millimeter-wave applications.