A Broadside Yagi-Uda Antenna with Enhanced Gain for mm-Wave Applications

Abstract This work presents an original planar Yagi-Uda antenna utilizing only two metal layers to achieve broadside emission. The proposed design generates traveling waves and redirects them upwards, forming an oblique, highly directive main lobe. This feature facilitates integration into 2D array structures, distinguishing it from standard end-fire Yagi-Uda configurations, which are typically arranged linearly in one dimension. The implemented PCB prototype has a compact footprint of 12.5 × 20 mm 2 and is optimized for mm-wave 5G applications. Operating within the 34.5 to 41.5 GHz frequency band, the antenna achieves outstanding performance, with a maximum radiation efficiency of 98% and a measured peak gain of 12.5 dB. Notably, the broadside emission produces a narrow main lobe tilted by 30° at 38 GHz. Additionally, this study outlines key principles for scaling the design, enabling adaptation to diverse technologies, and ensuring broad platform compatibility.