Design of a Super Compact UWB Filter Based on Hybrid Technique with a Notch Band Using Open Circuited Stubs

Abstract

This paper presents a new design of a super compact Ultra wideband (UWB) band-pass filter (BPF) with rejection of X-band satellite applications. For covering the UWB bandpass, the proposed filter is realized using hybrid technique which is achieved by using a Microstrip-Coplanar waveguide-Microstrip transition. The basic structure consists of a modified microstrip in the top layer and CPW in the bottom layer. Later, open-circuited stubs are embedded in the top to implement in-band transmission zeros (TZ) so as to circumvent interference. The simulated results show that the UWB bandpass filter has a high adaptation (S11 ≤ −18 dB) and insertion loss better than 0.4 dB at the passband. The impedance bandwidths are about 114% (3–11 GHz) with upper stopband extends to more than 14 GHz with a depth of greater than 38 dB. In addition, the UWB BPF shows a flat group delay performance with a variation of about 0.15 ns over the entire bandwidth. A prototype of the filter is fabricated and tested. Good agreement is achieved between measurement and simulation. The proposed UWB BPF is compact in size with overall dimensions of 14 by 9.2 mm2. Consequently, the obtained results prove that the presented filter is suitable for UWB wireless devices.