The invention relates to a passive repeater for forwarding radio signals from a first device having a radio interface to a second device having a radio interface, wherein the passive repeater is configured to forward radio signals between an interior of a housing, which has a housing wall acting as a radio barrier, and an exterior, through the housing wall, wherein the passive repeater has a first antenna and a second antenna for this purpose, which are connected to each other by a passive and galvanic coupling, and wherein the first antenna can be arranged in the interior and the second antenna can be arranged in the exterior, and the passive coupling can be carried out through an opening in the housing wall, and wherein the first antenna can be inserted into the interior from the exterior through the opening and/or the second antenna can be withdrawn from the interior to the exterior through the opening. The invention further relates to a radio system having such a passive repeater, to a vehicle having such a repeater or such a radio system, to a bearing having such a repeater or such a radio system, and to a use of such a repeater or such a radio system.