In-Phase T-Junction: Study and Application to Gysel Power Dividers for High Power-Division Ratios Requiring No High-Impedance Transmission-Line Section

A novel Gysel power divider, which can be fabricated without a need for any high-impedance transmission-line section (TL), even for the power-division ratios higher than 15 dB, is presented. To derive its design formulas, a new study on the conventional in-phase T-junctions is carried out, and two conditions are newly derived for the arbitrary power-division ratios and perfect matching at all the ports, which can be applied for any symmetric or asymmetric Gysel power divider without any additional effort to design the isolation circuit. As a proof-of-concept demonstration, two prototypes I and II at the design frequency of 1 GHz are fabricated for the power-division ratios of 17 and 20 dB, respectively. Such power-division ratios have never been tried before not only for the Gysel power dividers but also for generic planar power divider topologies without the use of high-impedance TLs for the wider bandwidths. The measured results are in good agreement with the predictions.