Fourier-based transmission line ultra-wideband Wilkinson power divider for EARS applications

We propose a technique with clear guidelines to design a compact planar ultra-wideband (UWB) Wilkinson power divider (WPD) for enhanced-access to the radio spectrum (EARS) applications. The design procedure is accomplished by replacing the uniform transmission lines in each arm of the conventional power divider with varying-impedance profiles governed by a truncated Fourier series. While such non-uniform transmission lines (NTLs) are obtained through the even mode analysis, three isolation resistors are optimized in the odd mode circuit to achieve proper isolation and output ports matching over the frequency range of interest. For verification purposes, an in-phase equal split WPD is designed, simulated, and measured. Simulation and measurement results show that the input and output ports matching as well as the isolation are below -10 dB, whereas the transmission parameters are in the range of (-3.2 dB, -4.2 dB) across the 3.1 GHz - 10.6 GHz band.