An apparatus for determining the fill level of a fill substance in a container, comprising at least one antenna element. The at least one antenna element has a hollow conductor, wherein there is arranged at a first end region of the hollow conductor a coupling element for the out-coupling of transmission signals and for the in-coupling of received signals, wherein there is arranged at a second end region of the hollow conductor a radiating element directed toward the fill substance, a transmitting/receiving unit having a signal generator for producing the transmission signals. The transmitting/receiving unit determines the fill level of the fill substance in the container based on the travel time of the transmission- and received signals. The connecting line and/or the hollow conductor are/is embodied in such a way that the transmission signals are transmitted time delayed, so that the distance between the at least one antenna element and the surface of the fill substance is virtually increased and the received signal is isolated in time from disturbances of the transmitting/receiving unit, which arise in the case of producing the transmission signals.