Small-sized quasi-elliptic parallel coupled band pass filter using microstrip discontinuity corrections and multilayer-technique

In this article, we present a new technique to obtain a sharp symmetric response with lower losses for microstrip coupled‐line bandpass filters using the discontinuities correction method.The technique is verified by measurements and simulations. Simulated and measured results of the proposed filters are presented and show good agreements. Additionally, based on this work it will be shown that a new idea with the help of U‐resonators and multilayer‐technique may be used in the future to reduce more the size and to suppress the second harmonic in reject band of the structure. We think that the filter structure can be applied to improve the stopband and passband performances of other microwave circuits as well as other types of filters. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2433–2438, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26262