Theory and Experiment of Two-Section Two-Resistor Wilkinson Power Divider With Two Arbitrary Frequency Bands

In this paper, a novel design theory of two-section two-resistor Wilkinson power divider (WPD) is introduced. By selecting two different physical lengths of two-section transmission lines (TLs), two arbitrary frequency band WPD can be achieved. Compared with the former work, the designable frequency ratio range ii can be extremely extended from 1 <; μ <; 3 to 1 <; μ <; ∞, general design equations for characteristic impedances, physical lengths, absorption resistors, and frequency ratio ranges are newly derived and proved from even- and odd-mode analysis. Because of no capacitors or inductors, the proposed WPD can be used for high-frequency applications. Spurious band of S
₂₁
appears between two passbands under the condition of two different physical lengths; therefore, a fl-type dual-band transformer is newly introduced to replace single TL for spurious band suppression. We proved that fl-type structure could effectively suppress spurious band of S
₁₁
, maintain two arbitrary frequency passband of S
₂₁
, and provide an extra isolation band of S
₃₂
at center frequency. Finally, three proposed WPD examples with fl-type structure are selected with different frequency ratios, where frequency ratio μ = 4 in Example A, μ = 6 in Example B, and μ = 20 in Example C are designed and fabricated in the experiment. Measured results show good agreement with the theoretical results.