Compact and High‐Selectivity Dual‐Band Bandpass Filter with Tunable Passband for Wimax and Wlan Applications

Abstract

A dual‐band bandpass filter with compact size and high‐selective performance is presented using the combination of an embedded double E‐type stepped‐impedance resonator and open‐loop resonators. The proposed dual‐band filter has the capability to achieve different passband frequencies, both resonance frequencies can be conveniently and independently controlled without enlarging outline circuit size, and four transmission zeros near the edges of the passband are achieved to obtain a high‐level selectivity. A comparison of simulated and measured results verifies the design and shows that two central frequencies of the fabricated filter are located at the desired 2.5 GHz (WiMax application) and 5.4 GHz (WLAN application) with 3 dB fractional bandwidths of 14.0 and 10.3%, respectively. The measured return losses are higher than 20 dB, whereas insertion losses are less than 0.9 dB in each of the two passbands. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2106–2110, 2013

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