Low loss triplexer with wide stopband using CRLH-TL for WLAN/WiMAX/5G Wi-Fi applications

Abstract

ABSTRACT This paper reports the design and development of a planar triplexer for WLAN/WiMAX/5G Wi-Fi applications based on a composite right-/left-handed transmission line (CRLH-TL) with low passband insertion loss, high channel isolation, wide stopband and minimal fabrication complexity. Even- and odd-mode methods are used to extract resonant properties of the globe-shaped open stub loaded stepped impedance resonator (GSOSL-SIR). The transmission line model of the GSOSL-SIR is analyzed and based on that; three bandpass filters are designed at 2.4/3.5/5.5 GHz. The equivalent LC circuit model for GSOSL-SIR-based CRLH-TL is provided with all lumped parameters fully defined. Finally, Triplexer is proposed by connecting all the three bandpass filters where each channel shows measured center frequency of 2.4/3.48/5.52 GHz with 3 dB fractional bandwidth of 22.08/22.19/16.3%. The proposed triplexer achieves high channel isolation (>30 dB) and low in-band insertion losses (1.1/0.87/1.3 dB) for the three filter channels. Additionally, the triplexer has measured 20 dB rejection levels from 6.5 GHz to 14.64 GHz and 10 dB rejection levels from 6.22 GHz to 19.85 GHz. The observed concordance between measured, electromagnetic simulated and equivalent LC circuit simulated results supports the utility of the design method.