A Compact Dual-Band Planar Monopole Antenna Using Fractal Rings and A Y-Shaped Feeding Transmission Line

This paper presents a novel design approach of a compact dual-band monopole antenna with an overall size of 18.9x13x1.6mm(3). The proposed antenna is composed of a fractal ring shaped patch fed by a Y-shaped transmission line on the top side of the substrate and a second fractal ring along with a U-shaped ground plane on the bottom side. The second fractal ring, identical to the radiating ring, is loaded and a rectangular slot is etched at the top side of the ground plane respectively, to achieve dual-band characteristic and improve the impedance matching. The effect of standard ground-plane (SGP) of a laptop computer is incorporated in the design; the antenna is mounted on a SGP in order to investigate its performance. The antenna covers widely the frequency bands of the WLAN 2.4 GHz (2.2-2.52 GHz) and WiMAX 3.5 GHz (3.32-4.35 GHz), and exhibits an omnidirectional radiation pattern in the H-plane and a monopole like radiation pattern in the E-plane. A good agreement between the simulated and measured results indicates that the proposed dual-band antenna design is suitable for WLAN/WiMAX applications.