A Multiband Yagi-Uda Patch Antenna with Different Orders of Koch Fractal

Abstract This article explores the performance of a Yagi-Uda patch antenna with Koch fractal geometry of different orders on an FR-4 substrate. It exhibits multiband operation, enabling the use across multiple frequency bands. The proposed reflector features equally spaced slots. The radiating dipole element has a Koch fractal geometry of order 2, while the third directive element of the antenna is shaped as a Koch fractal of order 1. The antenna was designed and simulated using CST Studio® from 1 GHz to 10 GHz. After fabrication, measurements with a vector network analyzer (VNA) verified the presence of 11 operational bands with resonance frequencies centered at 1.265 GHz, 1.545 GHz 2.59 GHz, 2.7 GHz, 3.05 GHz, 3.9 GHz, 5 GHz, 5.18 GHz, 5.71 GHz, 6.20 GHz, and 8.72 GHz. It results in an aggregate bandwidth of 652 MHz (Ultra-Wideband, UWB) with applications in a range of protocols and technologies. The antenna dimensions are only 100 mm x 120 mm, resulting in a compact size.