Dual-mode square ring resonators for design of millimeter-wave ultra-wideband bandpass filter

In this article, a millimeter-wave ultra-wideband (UWB) bandpass filter is proposed and implemented by cascading two dual-mode square ring resonators loaded with lambda(0)/4 and 3 lambda(0)/4 open timing stubs, aiming at transmitting the signals in the UWB passband of 22-29 GHz. Formulae based on even- and odd-mode analysis are derived to facilitate the design of transmission zeros of these ring resonators. Because of the transmission zeros in the lower and upper stopbands, the proposed filter exhibits sharp attenuations near the passband as well as very wide stopband. The measured responses of the filter agree well with the design simulation, and satisfy well the Federal Communications Commission's indoor limit on millimeter-wave UWB applications over very wide frequency band. (c) 2008 Wiley Periodicals, Inc.