CAD of Left-handed Transmission Line Bandpass Filters

Owing to the negative and nonlinear nature of phase constant (fl) versus frequency, left-handed transmission lines (LH-TLs) can present higher values of fl as compared to right- handed ones. As such, left-handed (LH) structures are promising in terms of size minimization of microwave circuits. In this paper, a simulation study leading to computer aided design (CAD) of LH-TL bandpass fllters is presented. Motivated by a recent work, in which, a bandpass fllter is realized by coupling several LH units, we propose a new structure consisting of a single unit with composite right/left-handed (CRLH) characteristics. The structure ofiers several advantages over traditional fllters, e.g., compact dimensions and low loss. A new CAD algorithm for automated fllter design, which can be valuable to designers, is demonstrated through an example.