There is much recent interest in antennas constructed from conductive fibers and textiles. Traditionally, antennas are constructed with metallic elements which are sufficiently conductive that they can be treated as PEC with little loss of accuracy. However, the new conductive textile materials have electrical properties sufficiently different from standard metallic conductors to affect the accuracy of computer modeling and analysis. Accurate antenna modeling requires knowledge of the effective conductivity of the textile antenna elements, a topic that has not been adequately addressed to date in much of the available literature. This work presents an experimental method for the determination of the radio frequency parameters for conductive textile materials and shows how such experimentally derived material parameters can be used to enhance the accuracy of computer antenna designs and models.