Broadside couplings for high-selectivity microstrip filters

This paper describes a number of broadside-coupled microstrip structures an d their use for the implementation of high-selectivity multilayered filters . The broadside configuration allows for the introduction of cross coupling s between nonadjacent resonators. The cross couplings can then be used to i mplement transmission zeros that can significantly increase the selectivity of the filters. Furthermore, the investigation shows that the amount of co upling can be considerably increased if the resonators are broadside couple d, thus easily allowing the implementation of broadband filters. Measured r esults are shown to agree with predictions, thereby fully validating the ne w structures described. (C) 2001 John Wiley & Sons, Inc.