Quasi-Reflection Less Bandpass Filter Using Distributed - Elements

This paper discuss the design and simulation of a third-order quasi-reflectionless BPF using lumped elements and microstrip coupled lines. The filter has a center frequency of 3.715 GHz and demonstrates non-reflective characteristics by employing absorptive resistors. Its bandwidth ranges from 2.3 to 6 GHz. These filters are essential circuit elements in many applications as they exhibit very low reflections at the out band and minimal insertion loss in passband. The suggested design includes standard microstrip coupled-line sections and open and short circuit impedances with absorptive resistors. The simulation results display the return loss and insertion loss for schematic and layout diagrams of the bandpass filter in the bandwidth of 2.3-6 GHz, represented as S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> and S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</inf>, respectively, which are below 20 dB and 1.0 dB. The lower and upper sideband reflections are less than 7 dB.