Wilkinson Power Divider With Fixed Width Substrate-Integrated Waveguide Line and a Distributed Isolation Resistance

This letter proposes a new modified architecture of the Wilkinson power divider (WPD) based on fixed-width substrate-integrated waveguides (SIW) lines with optimal network isolation resistors. To overcome the problem related impedance variation of the SIW line without altering other characteristics, a reference impedance is used in all parts of WPD. The length of branches is designed considering this constraint. The isolation resistance is formed of n surface-mounted parallel resistors to reduce considerably the SIW-resistance discontinuity effect. The optimal number n of resistors depends on the package of the used surface-mounted resistor and thickness of the used substrate. The determined optimal number of resistances gives enhanced isolation performance over a wide frequency band. The results of measured manufactured prototype show 20-dB isolation bandwidth of 18% around 10 GHz. Compared with the previous designs, this new design offers smallest loss and broader bandwidth with simpler structure.