Multi Mode Resonators Based Triple Band Notch UWB Filter

Abstract

A compact and highly selective triple band notch UWB (3.3 GHz -10.7 GHz) filter is presented. Low insertion loss UWB pass band characteristics is achieved by two coupled multi mode resonators (MMR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> and MMR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ). Desired triple band notch characteristics and sharp UWB filter characteristics are achieved by introducing transmission zeroes (TZs). Three band notches are implemented to mitigate the potential interferer signals at 4.42 GHz (Radio altimeter ITU band), 5.54 GHz (WLAN) and 7.64 GHz (Satellite communications). Wide upper stop band is realized by incorporating a stepped impedance low pass filter structure. The filter is realized on a RT/Duroid 5880 substrate (ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> = 2.2 and thickness = 0.8 mm) and measured to validate the predicted results. The group delay of the filter is relatively constant and less than 0.45 ns over the desired pass band.