In the present study, a newly designed polyester substrate-based textile microstrip patch antenna operating in the 3.5 GHz band is proposed for smart clothing in broadband wireless applications. The motivation behind this work stems from the lack of comprehensive studies that address all critical aspects—including off-body performance, fabrication, testing, on-body evaluation, bending analysis, and SAR assessment—while specifically focusing on polyester textile antenna designs for the 3.5 GHz band in next-generation wearable systems. The antenna of small dimension 30×20×0.8 mm³ is designed and simulated in CST, followed by prototype fabrication and subsequent measurements to validate the simulation results. Slotting and partial grounding techniques are employed in the design for improving the radiation performance of the antenna. The effectiveness of the antenna has been assessed under the off-body and on-body conditions. Bending analysis under various bending conditions is performed to assess

the antenna’s flexibility and suitability for wearable applications. Experimental results obtained from the fabricated antenna in free space and on-body scenarios show agreement with simulation data. Moreover, the specific absorption rate (SAR) analysis confirming that the antenna complies with IEEE safety standards. The proposed antenna achieves a wide bandwidth of 1.17 GHz (operating range of 3.11-4.27 GHz), a higher radiation efficiency of 94.52%, and a moderate peak gain of 2.59 dB. It covers 5G NR (n77, n78), C-Band (Radar/WiMAX), CBRS, and Extended C-Bands used for wearable broadband applications. Hence, the proposed antenna is robust and well-suited for smart clothing applications in wireless broadband applications as it combines good radiation characteristics and stable performance under bending, while maintaining safe SAR levels and a compact textile-compatible design.