Design of the UWB bandPass filter based on the 1 cell of microstrip CRLH-TL

The design of a new UWB bandpass filter is proposed, which is based upon the microstrip composite right- and left-handed transmission-line(CRLH-TL). In order to bring the remarkable improvement in an attempt to reduce the size, taking the features of the conventional periodic CRLH-TL, only one unit of the structure is chosen. So the component less than a quarter-wavelength is realized to achieve the ultra wide band filtering without the loss of the original advantage of the CRLH-TL. Guaranteeing the compactness in size, the interdigitated coupled lines are used to realize the strong coupling for the design that will be shown to have the size of ´guided wavelength/9.4´, the fractional bandwidth over 100%, the insertion loss much less than 1 dB, and the flat group-delay with an acceptable return loss performance in the predicted and measured results.