This paper presents a new compact single-feed circularly polarized S-band antenna for Nanosatellite TT&C applications. The antenna is composed of two crossed dipoles printed on both sides of a substrate, center-fed by a 50Ω coaxial cable. It provides a unidirectional pattern thanks to a reflector placed below the antenna. In order to reduce the size of the structure, this reflector is composed of an Artificial Magnetic Conductor (AMC). The bandwidth of the antenna is 17% (1.98 -2.35 GHz) and covers the 2.025-2.110GHz TeleCommand band and the 2.2-2.29 GHz TeleMetry band. The size of the entire structure including the radome and the satellite interface is 0.58λ min of diameter and 0.081λ min of height where λ min is the wavelength at the lowest frequency. This new antenna concept will be used in the EYESAT CNES Program in 2017.