Design of Folded Multilayer Microstrip Tri-Band Hairpin Band Pass Filter

This study presents a novel approach for realizing miniaturized multi layer folded tri band micro-strip band pass filter for Wireless Local Area Network (WLAN) and Worldwide interoperatability for Microwave Access (WiMAX) applications. The proposed filter consists of a pair of folded hairpin stepped impedance resonators and pair of open loop resonators to achieve tri-band performance. The size of the folded micro-strip tri-band filter is reduced by nearly 60% due to the structural folding arrangement of SIR compared with conventional multilayer triband filter. The folded hairpin resonator helps to reduce the size of the filter. The stepped impedance resonators are designed to operate at the first and third pass bands and the open loop resonators at the second pass band. The design methodology of the tri-band band pass filter was presented. The simulated results of proposed tri-band filter were compared with the conventional one and tabulated.