Abstract
A novel compact ultra wideband (UWB) bandpass filter (BPF) based on composite right/left handed transmission line (CRLH TL) is reported in this paper. The proposed UWB BPF is designed and developed by coupling of two unit-cells of via-less CRLH TL, excited by asymmetrical coplanar waveguide (CPW) feed-line. The unit cell of CRLH TL is designed using series interdigital capacitor (IDC) in shunt with the shorted inductive stub. Because of the CPW-fed, no via is required to get the shunt inductance for the realization of CRLH TL, which minimizes the fabrication steps. The filter is compact in size 11.9 x 6 mm 2 . The proposed filter exhibits the return-loss (|S 11 |) more than 11.2 dB and insertion-loss (|S 21 |) less than 0.5 dB and low and flat group delay response throughout the passband, 3.3 GHz to 13.0 GHz. The proposed UWB BPF also shows the good stopband rejection (|S 21 | > 20 dB and |S 11 | < 0.8 dB) from 13.6 GHz to 15 GHz and steep roll-off from passband to stopband. The fractional bandwidth (FBW) of the filter is found to be 119 %. The equivalent lumped circuit model of the filter is obtained through Ansoft Designer. All simulated results are extracted through method of moment based simulator, IE3D. Agilent vector network analyzer (VNA) is used to get the measured results. All measured results are found in close similarity with the simulated results.
Highlights
The left handed metamaterials can be realized mainly by two methods, firstly, using periodic arrangement of split ring resonators and thin metallic wires and, secondly by dual of conventional right handed transmission line, i.e. by periodic arrangement of series interdigital capacitors in shunt with the shorted stubs to ground
EQUIVALENT LUMPED CIRCUIT MODEL ANALYSIS The equivalent lumped circuit mode of the proposed ultra wideband (UWB) bandpass filter (BPF) shown in Fig. 1 is depicted in Fig
MEASUREMENT RESULTS AND DISCUSSION Based on the optimized physical parameters listed in Table I, the proposed UWB BPF shown in Fig.1 is fabricated and its performance parameters are measured using Agilent vector network analyzer
Summary
The left handed metamaterials can be realized mainly by two methods, firstly, using periodic arrangement of split ring resonators and thin metallic wires and, secondly by dual of conventional right handed transmission line, i.e. by periodic arrangement of series interdigital capacitors in shunt with the shorted stubs to ground. The first and second methods are respectively known as resonant and non-resonant approach of realization of left handed metamaterials. Due to large in size and lossy in nature, the resonant approach is not well suited for the realization of left handed metamaterials [1]. Since 2002 the U.S Federal Communications Commission (FCC) [2] has regularized the unlicensed use of UWB frequency band 31. GHz to 10.6 GHz, the research in the field of UWB bandpass filter. Brazilian Microwave and Optoelectronics Society-SBMO received 08 Sep 2016; for review 08 Seo 2016; accepted 12 Jan 2017. Brazilian Society of Electromagnetism-SBMag has gained much attention and challenges. The design of ultra wideband components need much efforts and attentions as it requires the good selectivity, low insertion-loss and low and constant group delay throughout the passband
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