A single-layer substrate-integrated waveguide (SIW) filtering power divider (FPD) with fully differential operation at 28 and 39 GHz is proposed in this letter. This FPD consists of three SIW cavities where the differential and common modes of each cavity were properly designed to form three-pole dual passbands, facilitate deployment of isolation resistors, and introduce transmission zeros while attaining high in-band common-mode rejection. To improve the output return loss and isolation in dual bands, a novel and simple approach to find the proper location of isolation resistors is presented. At operating frequencies, the measured differential-mode input or output return loss, minimum insertion loss, isolation, and common-mode suppression are >14.1 dB,< (3 + 2.2) dB, >14.9 dB, and >30.3 dB, respectively. The amplitude and phase imbalances between outputs are < 0.48 dB and <4.2°, respectively.
- common-mode rejection
- filtering power divider (FPD)
- isolation resistor
- substrate-integrated waveguide (SIW)