负群时延电路研究综述：特征、现状与展望

近年来,负群时延电路由于其异常的电磁波传播特性及广泛的应用前景备受关注.首先,介绍了负群时延与超光速现象的相关概念,阐述了负群时延现象的产生机理及负群时延电路的频域特征;然后,重点讨论了基于左手材料、谐振器与耦合微带线3种主要负群时延电路的组成形式与特点;指出了目前电路的主要问题在于其固有的高损耗、窄带宽特点及负群时延值极限;最后,对负群时延电路未来的研究方向进行了展望,以期为负群时延电路的研究与应用提供一定的参考.

Research review on negative group delay circuits: property, progress and prospect

Due to its anomalous electromagnetic transmission characteristics and promising applications, neg-ative group delay circuit ( NGDC) has received a lot of attention in recent years. Firstly, related definitions on negative group delay ( NGD) and superluminal phenomenon are introduced, followed by the illustration of the physical mechanisms and frequency-domain properties of NGDCs. Then the structures and characteristics of typical NGDCs employing left-handed material, resonators and coupled microstrip lines are mainly dis-cussed. It is found that present NGDCs are inherent with drawbacks such as high insertion loss, limited bandwidth, and asymptotic limits of NGD value. Finally, developing trends of NGDC researches are pointed out. All of these are supposed to provide some reference for NGDC researches and applications.