Miniaturized Filtering Wilkinson Power Divider With Hyper-Wide Stopband/Isolated Band by Overcoupling Principle

This letter presents an elegant method to implement a two-way two-stage filtering Wilkinson power divider (FWPD) with a hyper-wide stopband and isolated bandwidth. Stepped-impedance resonators (SIRs) are used in the proposed FWPD. By simply designing a few parameters, multiple spurious bands can be naturally overcoupled (suppressed) while achieving the desired passband specification. Wide stopband and isolated band are attained together with low design complexity. For validation, an FWPD is designed, fabricated, and measured. The measured results suggest a 20-dB stopband of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$24.04~f_{0}$ </tex-math></inline-formula> and a 20-dB isolation bandwidth of beyond <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$27.5~f_{0}$ </tex-math></inline-formula>, with a compact size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.008~\lambda _{g}^{2}$ </tex-math></inline-formula>.