Design Theory of Dual-Band Wilkinson Power Divider with Different Frequency Ratio Ranges

In this paper, a design theory of dual-band Wilkinson power divider (WPD) with different frequency ratio ranges is presented. By selecting different physical lengths ratio of two transmission lines (TLs), the frequency ratio range can be selected accordingly, where physical lengths ratio is defined as l
₁
/l
₂
. A 3-type transformer is used to replace the first TL in WPD application to enhance the spurious band suppression. The design theory with l
₁
<; l
₂
has been reported, and the second TL was replaced by the 3-type transformer in the former work. Compared with the previous work, it is proved by this work that the case of l
₁
> l
₂
also can be realized physically. The design charts and design examples are summarized. The comparison of S-parameters between two cases is also given in this paper. Finally, one experiment with 3-type transformer is fabricated, the simulated and experimental results are matched very well.