DOE based design method for coupled-lines narrow bandpass filter response improvement

International audienceIn this paper we discuss about various modifications of classical coupled-lines narrow bandpass filter to obtain some frequency response improvement. The first modification concerns the broadening of the resonator strip-widths to improve their unloaded Q-factor. The second modification consists in replacing the in/out coupled lines section by tapped lines feeding. Finally a transmission zero is added using a geometrical modification that favor coupling between non-adjacent resonators. The theoretical investigation is carried out through a DOE based sensitivity study using both a circuit modeling approach and a full wave analysis. Theoretical and experimental results on microstrip filters are compared.In this paper we discuss about various modifications of classical coupled-lines narrow bandpass filter to obtain some frequency response improvement. The first modification concerns the broadening of the resonator strip-widths to improve their unloaded Q-factor. The second modification consists in replacing the in/out coupled lines section by tapped lines feeding. Finally a transmission zero is added using a geometrical modification that favor coupling between non-adjacent resonators. The theoretical investigation is carried out through a DOE based sensitivity study using both a circuit modeling approach and a full wave analysis. Theoretical and experimental results on microstrip filters are compared