Dual band filter design using real frequency technique and frequency transformation

In this work,we present a frequency transformation based dual-band filter design approach using scattering based real frequency technique. in the design process,conventional low-pass to band-pass frequency transformation is integrated with the simplified real frequency technique to construct double pass-band filters. the approach is particularly advantageous for designing matching filters between different termination resistances. as an alternative to a direct low-pass to dual-band frequency transformation,the use of dual-band mapping on a normalized band-pass prototype is investigated for efficient control of the passbands. application of the proposed approaches for dual-band filters is presented by comparative design examples.