A compact 15:1 unequal power divider using composite transmission lines

A new structure of unequal power divider with a power division ratio of 15 is proposed in this paper. The new guiding structures constructed by a composite line consisting of distributed and lumped elements can be applied to release the fabrication limitation of microstrip lines with high/extra low characteristic impedance, and then reduce the overall circuit area. For verifying the validity of the proposed structure, a 15:1 Wilkinson power divider operating at 1 GHz was designed and fabricated. The measured bandwidth of less than 15 dB return loss is about 8%, while the isolation is better than 20 dB. The measured insertion losses of two output ports are about 12.66 dB and 0.71 dB at 1 GHz, respectively, while the phase difference between them is less than 4.6o.