Microstrip Bandpass Filter Using Fractal Based Hexagonal Loop Resonator

Microstrip filters have been widely used in many RF/microwave systems. Compact and high performance microwave bandpass filters are highly desirable in wireless communication systems. In order to meet the demands, the microstrip dual-mode resonators have been widely used for microstrip bandpass filters. This paper presents a hexagonal microstrip loop resonator bandpass filter(BPF) using Koch curve approach. The filters designed with fractal geometry are having reduced return loss and good pass band performance. Compared to conventional design, the proposed filter shows a 8% fractional bandwidth at the central frequency 1.575 GHz, with return loss better than 10 dB. The central frequency and insertion loss of the proposed filter are reduced by 20% and 1.2 dB, respectively. So size reduction and improved insertion loss performances are obtained.