An Elliptic-Function Bandpass Filter Utilizing Left-Handed Operations of an Inter-Digital Coupled Line

Abstract

A new elliptic-function bandpass filter (BPF) is proposed, which utilizes an inter-digital coupled line (IDCPL) as a left-handed transmission line. The IDCPL is employed in order to realize a negative coupling between non-adjacent resonators in a wideband BPF. As the authors' knowledge, the left-handed operations of the IDCPL has rarely utilized before, although the IDCPL itself has been widely used in many microwave circuits without being paid attention to the left-handed operations. Measured characteristics of two BPFs are presented in this paper, one is targeted for 3-4GHz WiMAX systems, and the other is for 3-5GHz ultra wideband communication systems (UWB).