ABSTRACTIn this article, a compact wideband bandstop filter in the form of open stub combination is proposed. The wideband characteristic of the proposed bandstop filter is due to electrical coupling at the ends of the two open stubs. A stopband is approximately improved by 52% (rejection depth: −20 dB) compared with the case that the end of open stub is uncombined. Proposed structure increases the skirt selectivity and elastically controls the frequency bandwidth and rejection depth. Furthermore, stopband is extended about 125% (rejection depth: −20 dB), when spurline is added to the proposed bandstop filter without any size increment. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2701–2703, 2013