A Miniaturized Microstrip Dual-Band Bandpass Filter using Folded UIR for Multimode WLANs

A novel microstrip dual-band bandpass filter (BPF) using folded half-wavelength uniform impedance resonator (UIR) with high selectivity is presented. The proposed filter with two tuneable passbands has advantages such as compact size and simple structure. The passband frequencies have been adjusted for 2.4 GHz and 5.2 GHz wireless local area networks (WLANs). The overall size is reduced by 30 % in comparison with the two section radial stepped impedance resonator (SIR). The measured insertion loss is less than 0.18 dB and 0.5 dB in the first and second passbands, respectively. Also the measured return loss is more than 30 dB and 20.73 dB in the first and second passbands, respectively. There is a good agreement between the measured and the simulated results.