Tunable dual‐band bandpass filter for WLAN applications

This article proposes the design of tunable dual-band filters for multiband multistandard systems, specifically for wireless local-area network applications. The two main goals are to provide frequency tunability in the second band while maintaining the first band fixed and to obtain a structure capable of offering a ratio between the second and first passband center frequencies larger than 2. To this end, a capacitively loaded stepped-impedance resonator is proposed for integration in dual-band filters. A detailed analysis of the resonator is provided. A filter has been designed to validate the concept. It demonstrates operability in wireless local-area network frequency bands, with a fixed first band at 2.45 GHz and a second band which can be tuned between 5.75 GHz and 5.25 GHz. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2025–2028, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24550