A novel miniature ultra-wideband microstrip filter using a short-ended interdigital coupled-line unit

Abstract

In this paper, a novel miniature ultra-wideband (UWB) microstrip bandpass filter is proposed. The filter consists of a short-ended interdigital coupled-line unit fed by stepped-impedance lines. Through adjusting the stepped-impedance feed lines, an ultra wide passband with equal-ripples can be obtained. The filter also has multiple transmission zeros on both sides of the passband, exhibiting favorable passband skirt property. The filter is fabricated, and its measured results show good agreement with the simulated responses.