Abstract: A novel compact dualband bandpass filter (BPF) is designed for applications of wireless local area network (WLAN) IEEE 802.11 b/a (2.4/5.2 GHz). The filter is composed of folded stepped impedance resonators (SIRs) and two stubs with one transmission zero. The two passbands are centered at the basic resonant frequency and the firstorder spurious frequency. To match the input and output impedances and improve performance of the two passbands, a tapline is used to feed the coupling resonator at zero degree. Simulation results show that the two center frequencies are located at the desired 2.4 and 5.2 GHz with 3 dB fractional bandwidths of  6.3% and 3.4%, respectively. The measured results are in general agreement with the simulation results.

Key words: bandpass filter (BPF), dual-band, stepped impedance resonator (SIR)