This paper describes a wideband power divider using a new type of transmission line transformer (TLT) to change impedance from 50 to 25Ω. A prototype of the power divider to connect two 50-Ω coaxial cables to the 25-Ω output ports of the proposed TLT was fabricated. The reflection characteristics of the proposed TLT were less than -15dB over the range 54-907MHz. The reflected power of the power divider was less than -14dB, and the relative amplitude and phase difference between two outputs of the power divider were within ± 0.15dB and ± 1.0° over the range 100-900MHz.