Wideband Bandpass Filter Using Coupled Lines With Multiple Transmission Poles and Good Outband Performance

A wideband bandpass filter using coupled lines with sharp roll-off shirts is proposed in this paper. Seven transmission poles within the passband and high out-band rejection performance can be realized through even-and odd-mode input impedance calculations. For demonstration, a wideband bandpass filter prototype centered at 1.5 GHz with high-stopband rejection is designed and fabricated. Good agreement between the simulations and measurements validates the design idea.