Realization of Even Transmission Zeros for Filter Without Cross-Couplings

摘要

A new method is proposed to produce even finit transmission zeros without any cross-coupling between the resonators of f lter, by loading the second-order extracted-pole unit (EPU) composed of two mutual coupled resonators at the input or output port of the f lter. An arbitrary distribution of f nite transmission zeros on the imaginary axis can be achieved by adjusting the resonant frequencies of resonators in the EPUs and the coupling strength between them. The f nite transmission zeros can be symmetrically or asymmetrically distributed about the center frequency of the filt r, even all on the same side outside the passband of the filt r. And the topological structures of these filt rs are given in this paper. Besides, Cauchy method is adopted to analyze the proposed EPU conf guration f lter as well. This paper not only discusses how to implement a pair and two pairs of f nite transmission zeros, and how to control the distribution of f nite transmission zeros, but also gives multiple sets of computer-aided synthesized normalized coupling matrices. Based on this, an eighth-order quasi-elliptic function high-temperature superconducting filt r with two pairs of finit transmission zeros was designed on a double-sided YBCO/LaAlO3/YBCO f lms to verify the feasibility of this new structure.