A thermal sensitivity analysis is performed for an Inverted-F antenna (IFA) at the worst-case thermal condition (reentry phase) of a typical sub-orbital sounding-rocket spaceflight. Electromagnetic simulations show that a 300 Celsius change in the IFA temperature, mainly caused by the aerodynamic heating, increases the reflected power by 1% and decreases the antenna gain by 2.5%. The results show that the degradation of antenna performance and the telemetry link quality is negligible. Therefore, the IFA is a good antenna choice for similar sounding rockets from the thermal reliability point of view.