On the relation between a negative refractive index transmission line and chebyshev filters

The relation between composite right/left handed transmission lines (CRLH TL) and lumped element Chebyshev filters is discussed in this paper. A CRLH TL in the balanced case can be regarded as the central part of a low-ripple high- order Chebyshev band-pass filter (BPF). The balanced case of the CRLH TL is automatically satisfied in the mapping from a prototype Chebyshev low-pass filter (LPF) to a BPF. Moreover, once the ending sections are take into consideration, both a better impedance matching is achieved as well as a reduction of the large ripples close to the cut-off frequencies for a finite length CRLH TL. Therefore, a CRLH TL in the balanced case may be designed from a Chebyshev filter exhibiting an improved performance.