Multi-transmission Poles Dual-band Bandpass Filter with Extended Bandwidth

In this paper, a novel dual-band bandpass filter with multiple transmission poles is proposed involving 4G and 5G bands. Its circuit configuration is composed of the modified coupled-line structures and step-impedance open-circuited stubs. The analyzed cases are provided in detail. For demonstration, a design prototype operating at 2.4 GHz and 5 GHz with 15-dB return loss and stopband rejection at least is simulated, fabricated, and measured. Good agreements between simulated and measured results are obtained.