Planar bandpass filter for ultrawideband communication systems

Abstract

A broadside-coupled structure is used to build a planar bandpass filter with ultra-wideband (UWB) performance. The design is aimed at achieving a passband that covers the frequency range from 3.1 GHz to 10.6 GHz as required by the modern UWB indoor and outdoor communication systems. To achieve a wide upper stopband, a stepped impedance resonator is employed to suppress the harmonic responses outside the band of interest. The presented results confirm ultra passband performance. Furthermore, the device has a wide upper stopband that extends above 20 GHz, and. It shows a flat group delay with less than 0.1 ns peak-to-peak variation across the passband revealing a distortionless performance when operating in pulsed RF systems. The designed coupler has a compact size of 1.2 cm×1.8 cm.