Design Validation of Compact UWB Bandpass Filter using Stepped-Impedance Stub and DGS Techniques

In this work, an ultra-wideband compact bandpass filter is developed. The filter structure is based on symmetrical pair of coupled lines, stepped-impedance stub and rectangular defected ground structure slots. A prototype of the obtained structure is fabricated and measured where a good agreement is noticed between simulated and experimental results. Good performances in terms of ultra-wide impedance bandwidth, from 2.9 to 10.6 GHz with a fractional bandwidth of 118.8 %, return loss better than 13 $\text{dB}$, upper stopband attenuation higher than 20 dB up to 16 GHz and a sharp selectivity are obtained. The filter bandwidth makes it suitable for the several applications operating in this frequency range.