Miniature filtering power divider with increased isolation bandwidth

A novel filtering power divider (PD) with an extended isolation bandwidth is proposed. Adopting a frequency-dependent resistor-inductor-capacitor isolation network enabled designing and improving isolation performance. An embedded 90° filtering line was realised by employing two coupled quarter-wavelength resonators to achieve a bandpass response and a compact circuit size. The filtering PD was designed and implemented at a centre frequency of 1 GHz, and the isolation bandwidth (> 20 dB) was extended from DC to 2.2f₀.