Application Of Split Ring Resonators On Microwave Filters

Since the SRR, which is a unit cell of left-handed material, is proposed, much related works have been done. Besides its application on constructing metamaterial, the SRR can also be applied to design multiple microwave devices, especially microwave filters. Filter is a very important and common microwave component in modern microwave communication systems, almost every microwave systems have one or more filters. So whether a microwave system works well or not depends on the quality of the filters in it. Therefore, how to apply the SRR to microwave filter designing is a key issue which attracts much attention. In this paper, how to design different kinds of filters using the SRR is discussed, and main contents are as follows.First, a band-stop microstrip filter with a CSRR etched on its ground plane is designed, and a method to make its bandwidth broader by cascading several such filters is introduced, this method is proved to be effective. Besides, a method to transform a pair of coupling SRRs into a new structure is proposed. According to this method, three new structures are obtained, and several filters are designed based on these new structures. The features of these filters are also analyzed and compared.Second, SIW and HMSIW are introduced. An SIW filter based on CSRRs is designed and its characteristics are analyzed. Further studies about how to transform it into HMSIW filter are done, and the differences between them are analyzed. Besides, according to the peculiarity of the SIW, an SIW filter with a good performance based on a pair of BC-CSRRs is proposed, and relevant analysis are done. A further method of designing double-passband filters based on the filter mentioned above is introduced, and it has been verified. At last, this SIW filter is also transformed into a HMSIW filter.Third, the ACS structure is briefly introduced and its transmission characteristics are analyzed. Considering the fact that this structure has a bright prospect but lacks of application in designing filters at present, an ACS-fed filter consists of two SRRs is proposed. Different feeding patterns of this filter are compared. This filter expands the application scope of the ACS structure, and is a further demonstration that the ACS structure can be used in various microwave devices.