Compact dual-band bandpass filter using defected microstrip structure for GPS and WLAN applications

A modified defected microstrip structure (DMS) for designing a dual-band bandpass filter with independently controlled centre frequencies is presented. The DMS using an F-shaped spurline embedded into a uniform impedance resonator is applied to generate double-resonance characteristics. Based on this theory, a dual-band filter for GPS/WLAN applications has been designed, analysed and fabricated. It is compact and has easy fabrication. Measured results verify the validity of this design methodology. Also, this is believed to be the first report on the DMS in microwave dual-band filter design.