The utilization of wearable textiles in the antennas has shown a dramatic increase due to the recent challenges imposed on wireless devices to be miniaturized. For RFID purposes, a wearable antenna is meant to be a part of the clothing used. This includes tracking and navigation, mobile computing and public safety applications. Investigating the wearable textile antennas reported in the literature, it has been noted that when modeling the antenna using the commercially available EM simulators, the substrate (textile) has been dealt with as a solid homogenous material. This is fact is not the case, since the textile as a substrate is composed of woven threads (fibers). As a result, this adds some inaccuracy when comparing the simulated results with measured ones. In this paper, the textile antenna material, as a substrate, has been modeled in a way closer to the real practice. It has been modeled as horizontal and vertical fibers with different thread levels. A case study, representing a wearable textile antenna structure, has been investigated and the relevant textile material is being modeled using the proposed modeling technique. Simulation results of the antenna return loss responses using the proposed modeling technique; have shown to be more accurate than those obtained using the conventional modelling technique in that they are more close to measured results relevant to the antennas involved in the case study.