A compact dual-band bandpass filter for 2.4/5.2 GHz WLAN application

Abstract

In this paper, a dual-mode dual band bandpass filter using stub-loaded stepped-impedance resonators is proposed. Two short stub-loaded resonators are combined together in parallel manner with a common deformation of T-shaped feed line in order to design and analyze two resonators separately. The filter has two passbands centered at 2.45 GHz and 5.33 GHz with the respective fractional bandwidths of 7.7% and 7.1%. Moreover, to the needs of miniaturization, the proposed filter has very compact sizes of 0.15λg × 0.09λ_g, where the λ_g is the guided wavelength at the center frequency of the first passband. The group delay responses of the filter meet the requirement of the wireless communication system.