Dual-Band Filtering Power Dividers With Multiple Out-of-Band Transmission Zeros and DC-Blocking

• Published in: IEEE microwave and wireless technology letters (Print) 2024-07, Vol.34 (7), p.899-902
• Main Authors: Liu, Lei, Zhu, Lei, Wang, Zheng-Bin, Zhang, Ye-Rong
• Format: Article
• Language: English
• Subjects: Band-stop unit; Bandwidth; Design parameters; Design specifications; Dual band; Filtering; filtering power divider (FPD); Filtration; high band-to-band rejection; Mathematical analysis; multiple transmission zeros (TZs); Passband; Power dividers; Scattering parameters; Simultaneous equations; Topology
• ISSN: 2771-957X; 2771-9588
• DOI: 10.1109/LMWT.2024.3398603

In this letter, a novel topology of N-section dual-band filtering power divider (DBFPD) with multiple out-of-band transmission zeros (TZs) is proposed. The proposed design can not only realize the nth-order filtering function but also ( 2N + 1 ) TZs between the two passbands by different values of N. It mainly consists of 2( N + 1 ) coupled lines and 2( N - 1 ) shunted coupled stubs. A resistor-loaded three-line parallel coupled line is used to realize the expected power dividing ratio and good in-band isolation simultaneously. In addition, two stepped impedance stubs are introduced at output ports to improve frequency selectivity. Through mathematical analysis of its S-parameters, a set of simultaneous equations can be derived to obtain all the electrical dimensions according to the design specifications. To verify the correctness of the proposed technique, a dual-band FPD ( N = 1 ) prototype operating at 1.1 and 2.9 GHz with the fractional bandwidths of 18.2% and 6.67% is designed and fabricated. Good agreement between simulated and measured results evidently reveals that the proposed design holds its attractive advantages of multiple out-of-band TZs, good full-frequency isolation, high band-to-band and out-of-band rejections, inherent dc-blocking, and compact size compared with reported works.