Design of the quasi-0 dB backward wave-coupled line coupler using CRLH-TL based on stepped-impedance open stub-loaded dual-mode resonator

ABSTRACT

This paper demonstrates symmetric backward wave quasi-0 dB coupled line coupler (CLC) based on the globe shaped composite right/left-handed transmission line (GS-CRLH-TL). The proposed CLC shows quasi-0 dB backward wave coupling with measured maximum backward coupling level of −0.72 dB at 3.07 GHz. −3 dB bandwidth of the backward coupling region is from 2.75 GHz to 3.34 GHz, corresponding to fractional bandwidth (FBW) of 19.16%. The designed CLC shows good isolation of more than 43 dB in the backward coupling region in −3 dB frequency range from 2.75 GHz to 3.34 GHz. The measured value of return loss, at the center frequency 3.07 GHz, is more than 26.4 dB. Overall size of the fabricated CLC including 50 Ω feedline is 0.631λ_g × 0.455λ_g where λ_g is the guided wavelength at 3.07 GHz. Good concurrence is obtained between the simulated results, equivalent LC circuit model results and the measured results.

KEYWORDS:

• Composite right-/left-handed metamaterials
• globe-shaped CRLH-TL
• backward wave-coupled line coupler
• quasi-0 dB coupler

ORCID

Abhishek Kumar http://orcid.org/0000-0001-8471-7006

Additional information

Notes on contributors

Srikanta Pal

Srikanta Pal received his B.Tech. degree in Electronics & Communication Engineering from NIT Warangal, India in 1990 and M.Tech. degree in Microwave Engineering from Jadavpur University, Kolkata, India in 1992. From 1992 to 2000 he was with the R&D Antenna Lab of the Bharat Electronics Limited (BEL). In 2001, he joined the Oxford University as a Research Associate where he worked toward his Ph.D. on HTS Microwave Filters, which he completed in 2003. From 2003 to 2005 he was a visiting Faculty in the Centre for Advanced Research in Electronics (CARE) Department at the IIT Delhi, India. In 2005, he joined the Department of Electronics and Computer Engineering at the IIT Roorkee, India, as an Assistant Professor. He joined the Emerging Devices Technology Center at the Birmingham University as a Post Doctorate fellow in 2006 where he designed an HTS filter which is currently installed in the world's largest Telescope, Green Bank Telescope (GBT), West Virginia, USA. In 2008, he joined the ECE Department at the BIT Mesra where he is currently working as a Professor and Head of the Department. He is also a lifetime Research Fellow at the University of Birmingham. His research interests include RF Filters and Devices, MEMS, HTS Microwave filters, Antennas and Computational Electromagnetics.