Tunable dual-band filtering power divider with constant bandwidth and high selectivity

A tunable dual-band filtering power divider with constant bandwidth and high selectivity is proposed, which incorporates a wideband power divider with two tunable dual-band filters. The filter provides a tunable dual-mode dual-band filtering response, and realizes a 90 degrees phase shift to replace the middle quarter wavelength transmission line. As the bias voltage increases, the lower band increases from 1.1 to 1.5 GHz with a constant bandwidth of 40 MHz, while the higher band remains at 2.17 GHz with a fixed bandwidth of 60 MHz. During the wide tuning range, the return loss and isolation are always >15 dB, with a high selectivity due to multiple transmission zeros.