Characterization of dielectric properties, relative permittivity (εr, Dk, K), and dielectric loss tangent (Df, tan δ) are critical to RF design engineers. The parameter Dk drives characteristic impedance in transmission lines, coupling factors, and propagation velocity, so an accurate characterization is needed to avoid high magnitude reflections that cause poor power transfer through devices. Df is important for prediction of insertion loss in passive devices. If insertion loss is higher than predicted, then power transfer through a device may be too low and a higher power transmitter or more elements would be necessary. Presented here are four methods of extracting Dk and Df from dielectric samples of an unknown material and the pros and cons of each.