Abstract: A flat antenna for mounting on windowpanes of motor vehicles reduces the dimensions of the mass reference area of the mass plane, and the structural height without unfavorably influencing the functions and operating parameters of the antenna. The mass reference area has a trough-like shape, is centrally positioned under an aerial segment, and has conductive coating impermeable to the operating frequency of the antenna. The inside and outside conductors of the coaxial feed cable are connected to the aerial segment and mass reference area shifted to outside the aerial elements and thereby enables a significant reduction in overall dimensions.