Dual band bandpass filters based on strong coupling directional couplers

This paper presents a new type of dual band bandpass filter. It is based on strong coupling directional couplers inside a loop configuration. The proposed topology allows the control of the passbands bandwidths and the separation between passbands. The presented dual band bandpass filter exhibits wide stopbands with high rejection levels. To validate the suggested filter scheme, theoretical, simulated and measured results are presented for a dual band bandpass filter in CPW technology.