부산대학교 도서관

In this article, a novel dual-band (DB) filtering power divider (FPD) with full-frequency isolation is presented. The proposed topology consists of four coupled line sections (CLSs), two ring resonators (RRs), two shunted stepped impedance resonators (SIRs), two transmission lines (TLs), and one isolation network (INW). Through the mathematical analysis of its $S_{11}$ and $S_{21}$ parameters, simultaneous equations for characteristic impedances are derived with the proposed algorithm. In-band equal-ripple and six out-of-band transmission zeros (TZs) can be obtained. In order to realize full-frequency isolation performance, the closed-form design equations and their circuit simulation results of four types of INW are newly summarized and discussed in detail. The isolation level can be adjusted by virtue of the position of the extra TZ of $S_{32}$ parameter in the desired passband. For verification of the proposed synthesis theory, a general design flowchart is provided, several design examples are then selected and compared in detail. Finally, a DB FPD prototype is designed and fabricated for experimental demonstration. Measured results match the proposed theory very well, and the isolation level is below −20.4 dB in the full-frequency range.