Multidimensional reflection microwave barrier set up to monitor a plurality of two- or three-dimensional spatial regions (602, 603) extending in different spatial directions with respect to the reflection microwave barrier, comprising: a microwave transmitter (203, 204, 711) set up to generate and transmit a first microwave signal towards a first two- or three-dimensional spatial region and subsequently to generate and transmit a second microwave signal towards a second two- or three-dimensional spatial region; a microwave receiver (204, 711) set up to receive reflections of the first and second microwave signals; an evaluation unit set up to evaluate the reflections of the first and second microwave signal so as to determine whether a first object is located in the first spatial region or a second object in the second spatial region and to generate a first switch signal if the first object is located in the first spatial region and a second switch signal if the second object is located in the second spatial region; the microwave transmitter and the microwave receiver being configured in the form of a combined transceiver module; further comprising: a housing in which the microwave transmitter (203, 204, 711) and the microwave receiver (204, 711) are arranged, the housing being of a cylindrical construction; the reflection microwave barrier being characterised by an external thread on the front region of the reflection microwave barrier, set up for screwing the reflection microwave barrier into a fastening device, in particular a container opening, in a manner flush with the front. a microwave transmitter (203, 204, 711) set up to generate and transmit a first microwave signal towards a first two- or three-dimensional spatial region and subsequently to generate and transmit a second microwave signal towards a second two- or three-dimensional spatial region; a microwave receiver (204, 711) set up to receive reflections of the first and second microwave signals; an evaluation unit set up to evaluate the reflections of the first and second microwave signal so as to determine whether a first object is located in the first spatial region or a second object in the second spatial region and to generate a first switch signal if the first object is located in the first spatial region and a second switch signal if the second object is located in the second spatial region; the microwave transmitter and the microwave receiver being configured in the form of a combined transceiver module; further comprising: a housing in which the microwave transmitter (203, 204, 711) and the microwave receiver (204, 711) are arranged, the housing being of a cylindrical construction; the reflection microwave barrier being characterised by an external thread on the front region of the reflection microwave barrier, set up for screwing the reflection microwave barrier into a fastening device, in particular a container opening, in a manner flush with the front. a housing in which the microwave transmitter (203, 204, 711) and the microwave receiver (204, 711) are arranged, the housing being of a cylindrical construction; the reflection microwave barrier being characterised by an external thread on the front region of the reflection microwave barrier, set up for screwing the reflection microwave barrier into a fastening device, in particular a container opening, in a manner flush with the front.