Miniaturized dual-band BPF for WiMax/WLAN applications

In this paper a simple and planer new structure of dual band microstrip band pass filter (BPF) is proposed. The structure of the filter consists of stub loaded Interdigital Structure (IDS) sandwiched between two hairpin structures. Combination of IDS and hairpin structure achieves pass band response and stub loaded to IDS finger divides this pass band into two parts to create dual pass band behavior of the proposed filter. The pass band of the proposed filter covers 2.4GHz, 2.5GHz and 3.5GHz in first pass band and 5.8GHz in the second pass band. The structure of the filter is very small and simple to fabricate because structure is planar and any via or defected ground structure is not used. The filter is useful for the WLAN/WiMAX standards with good insertion loss. The FR4 epoxy material with dielectric constant of 4.4 and of thickness 1.6mm is used to design the proposed filter. The Performance of the proposed filter is found better and smaller in size than previously reported filters.