An antenna for high-frequency based measuring devices for determining a dielectric value of media is based on a high-frequency waveguide. The high-frequency signal is coupled in or out via a coaxial conductor that runs orthogonally through the axis of the high-frequency waveguide for this purpose. The conductor termination for the coaxial conductor extends extensively beyond the high-frequency waveguide in such a way that the coaxial conductor forms a defined capacitance in this region. In this way, the coaxial conductor is optimally matched to the high-frequency waveguide without having to integrate additional electrical components for this purpose.