Dual-band filter design of combined half and quarter wavelength SIRs for WLAN applications

This article presents a dual-band bandpass filter composed of lambda/2 and lambda/4 stepped impedance resonators for the wireless local area network applications. The filter covers both the operating frequencies of 2.45 GHz and 5.2-5.8 GHz. The doubly parallel-coupling mechanism is used in the filter design to reduce the insertion losses and to gain a wider bandwidth. The cross coupling configuration and the tapped-line I/O feed are adopted in this filter design to provide the attenuation poles for improving the signal selectivity and stopband rejection levels. Experiments were conducted to verify the circuit performance. (C) 2007 Wiley Periodicals, Inc.