A COMPACT UWB BANDPASS FILTER USING A CENTER-TAPPED COMPOSITE RIGHT/LEFT-HANDED TRANSMISSION-LINE ZEROTH-ORDER RESONATOR

摘要

The design of a new UWB bandpass filter is proposed, which has a center tapped microstrip composite right/left-handed transmission-line zeroth-order resonator (CRLH-TL ZOR). In an attempt to reduce the size, instead of the conventional periodic CRLH-TL, only one cell ZOR geometry is adopted and optimized to have the target UWB bandpass filtering. Along with this subwavelength filter, the matching parts working as a stepped impedance low-pass filter are suggested for good matching and stopband enhancement. The proposed filter is shown to have the overall size of "0.69 λ_g × 0.73 λ_g," 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.