LAUSR

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 0.631λg × 0.455λg where λg 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.