A New Microstrip Bandpass Filter Design Based on Hilbert Fractal Geometry for Modern Wireless Communication Applications

This paper introduces a new microwave narrowband bandpass filter with a miniaturized size as well as adequate transmission and return loss characteristics for use in modern wireless communication systems. The proposed filter design topology is based on a single-mode microstrip resonators constructed in the form of Hilbert fractal geometries of the 2 and 3 iteration levels. Filter structures have been designed for the ISM band applications at a resonant frequency of 2.4GHz using a substrate with a relative dielectric constant of 10.8 and thickness of 1.27mm.The most effective parameters on filter performance such as edge spacing and stub length variations have been introduced and evaluated . The performance of each of the resulting bandpass filter structures has been analyzed using a method of moments (MoM) based software package, Microwave Office 2007, from Advanced Wave Research Inc. In addition, it has been found that, the bandpass filters based on 3 iteration Hilbert geometry show a high degree of 2 harmonic suppression which accompanies the performance of most bandpass filter topologies.