Miniature dual‐mode dual‐band bandpass filter with improved passbands performance for 2.4/5.2 GHz WLAN application

Abstract

In this article, a miniature dual‐mode dual‐band bandpass filter (BPF) based on novel complementary center‐stub‐loaded stepped‐impedance resonators has been presented. By loading an open stub at the center of stepped‐impedance resonator, the center frequency of the fundamental even‐mode could be independently controlled, whereas that of the fundamental odd‐mode is fixed. A dual‐mode dual‐band BPF using complementary configuration is implemented with three transmission zeros. To validate the design and analysis, a prototype filter has been designed and fabricated with its two bands located at 2.4/5.2 GHz for WLAN. The measured performances show good agreements with those of the coupling matrix analysis and electromagnetic simulation. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1235–1238, 2014

Even–odd mode analysis for multiband bandpass filters having multiple resonators and its microstrip implementations

“…For multiband bandpass filter design, using multiple dual‐mode resonators under appropriate coupling is one of the most popular methods in the literature . By this way, passbands can be independently controlled by different resonators.…”

“…Besides, dual‐mode resonators are mostly used in multiband bandpass filter design. One of the most popular design methods is to combine dual‐mode resonators having different electrical lengths under appropriate coupling .…”

“…Conversely, using the same impedance formulas, calculations of perturbation capacitance and gap capacitance between the feedline and the resonator are also given in . In this study, dual‐band filter design has been achieved using two stacked ring resonators as in . However, these studies do not include the frequency response for dual‐band characteristics.…”

Dual‐mode stub‐loaded resonator and its applications to single‐ and dual‐band bandpass filters

“…In modern communication systems, single‐ and multi‐band BPFs have become key passive components of the microwave front‐end systems. Recently, various structures and techniques have being introduced to design BPFs with single or multiple passbands . Because of their compact size, simple design process, and good design flexibility, stub‐loaded dual‐mode resonators are widely used to realize single‐ and dual‐band BPFs .…”

“…Also, a tunable wideband single‐band BPF using stepped‐impedance SLR is presented in with high selectivity and deep stopband rejection. Dual‐band BPFs using novel SLRs are presented whose center frequency of the lower passband can be adjusted by changing the length of the loaded stub . A dual‐band BPF with controllable passbands is proposed using a variable characteristic impedance transmission line in SLR .…”