This letter presents the design of an unequal Wilkinson power divider with a high-dividing ratio. By proportionally reducing the impedances in both arms and employing T-shaped structure to replace quarter wavelength transmission lines with very low characteristic impedances, the proposed circuit can be constructed by microstrip lines with reasonable characteristic impedances, and therefore is easy to be fabricated and has planar structure. Furthermore, the value of isolating resistor can be flexibly adjusted to an available one. To verify our proposed idea, a 4:1 microstrip unequal power divider operating at 1.9 GHz is fabricated and tested. The ratio of highest to lowest characteristic impedances is only 2.2:1 in this 4:1 unequal power divider, compared with the ratio of 4.5:1 in conventional divider. © 2009 Wiley Periodicals, Inc.