The technological advances in electronic devices and the Internet of Things bring us to be surrounded by multiple sensors in the coming years. These devices should be conformable and adapted to small or irregular shapes and surfaces. This is why flexible materials are becoming important in this field thanks to their lightness, stretchability, and robustness especially in wearable electronics to get integrated on clothes for biomonitoring. Our proposal in this paper concerns the design, printing process, and performance of a novel antenna on a polyimide flexible substrate. It is based on a loop antenna and has dimensions of 40 mm×35 mm ×0.127 mm. Its very wideband behavior from 2.4 GHz to 4 GHz allows targeting S- Band applications such as L TE and Wi- Fi. Interesting performances are also achieved in terms of radiation patterns. At 2.45 GHz, the maximum antenna gain is about +2.6 dBi with an omnidirectional pattern but at higher frequencies, the antenna is more directive with a higher gain.