Design of Compact UWB Bandpass Filter with Improved Out-of-band Performance Using Distributed CRLH Transmission Lines

摘要

This study presents an Ultra-Wideband (UWB) filter with improved out-of-band performance. The proposed filter adopts novel Composite Right/Left-Handed (CRLH) Transmission Lines (TLs), which are modeled with distributed elements instead of lumped elements. A unit cell of the CRLH TLs is theoretically analyzed to derive the design formulas. The analyzing results confirm that the proposed structures are CRLH TLs. A novel UWB bandpass filter with improved out-of-band performance is designed and fabricated using the induced formulas. The measurement results show that the fabricated UWB bandpass filter has an insertion loss of less than 2.8 dB, a bandwidth of 2.8-10.4 GHz and a rejection of more than 18 dB from 11.6 to 23.4 GHz.