Compact dual-band microstrip bandpass filter using folded linear tapered-line resonator

A compact microstrip bandpass filter for WLAN dual-band applications is designed and fabricated. New folded linear tapered-line resonators (LTLRs) are proposed to provide dual-band behaviour besides reducing the size of the filter. A third-order Chebyshev filter is designed and fabricated using these resonators. A size reduction of 30% is achieved comparing with the traditional Hairpin filters using stepped-impedance resonators (SIRs). The prototype of the filter achieved insertion loss of 2dB and 2dB, return loss of 16dB and 21dB and bandwidth of 4.1% and 7.7% at 2.44 and 5.34GHz respectively, which are in good agreement with simulated results.