The invention relates to a varactor with an actuator, wherein the first actuator surface (2a) of the actuator is embodied on a substrate (1), and a second actuator surface (2b) is embodied on a first movable membrane (3a). In this context, the first movable membrane (3a) is arranged above an upper side (1a) of the substrate (1). A second movable membrane (2b) is arranged below a lower side (1b) of the substrate (1) facing away from the upper side (1a). The invention further relates to a varactor system made from two such varactors.