Design, Analysis, and Construction of an Equal Split Wilkinson Power Divider
The Wilkinson power divider is a well known device in the RF/microwave community used for splitting or combining signals. It is composed of simple transmission lines and a resistor, and takes advantage of the properties of quarter-wavelength transmission line sections to provide ideal power divider characteristics. Three different equal split Wilkinson power dividers are designed to operate near 1800 MHz and constructed using typical microstrip fabrication techniques. The three power dividers each feature a unique design to help determine how the microstrip layout can impact isolation and return loss. A circuit analysis of the general Wilkinson power divider schematic is performed to provide insight into the device characteristics as well as present a clear derivation of the correlating scattering matrix. A thorough comparison between the performances of each of the three different designs is conducted and the results are provided and discussed. The conclusions drawn from this investigation are that multiple Wilkinson power divider microstrip layouts can meet specific design criteria with similar results, indicating the robustness of the Wilkinson design. In particular and contrary to what is typically claimed within the RF/microwave community, a power divider featuring straight, parallel quarter-wavelength sections showed no degradation in isolation (or negligible effects of coupling) when compared to a power divider with curved quarter-wavelength sections.