Multiband antenna assembly for transmitting or receiving signals in at least two frequency bands , comprising a monopole antenna with a top substrate and a base substrate having defined dimensions and shape, wherein • the top substrate and the base substrate are arranged with defined distance relative to each other and define a cavity , wherein a first frequency band is basically defined by the dimension of the top substrate , in particular of the top and the base substrate , and in particular by the defined distance, • the top substrate comprises a set of at least four slots (14a-d,44), wherein a second frequency band basically is defined by the design and arrangement of the at least four slots (14a-d,44), the second frequency band is different from the first frequency band , • the cavity is designed so that for the first and the second frequency band the monopole antenna has preferred monopole sending and/or receiving directions substantially parallel to the extension of the substrates, in particular horizontally, • the top substrate is configured to provide a basis for attaching an additional sending and/or receiving unit which provides a preferred sending and/or receiving direction substantially orthogonal to the preferred monopole sending and/or receiving directions, and to provide a ground plane for the additional sending and/or receiving unit, • wherein the set of at least four slots (14a-d,44) are arranged in an adjacent manner so that a size and a shape of the ground plane is defined by the slots, and • the antenna assembly comprises a feed configured to transmit signals to and/or from the additional sending and/or receiving unit, wherein the feed is designed as a feeding pin protruding from the base substrate and extending to the bottom side of the top substrate in the region of the ground plane , wherein the feeding pin protrudes from the centre of the base substrate and extends to the centre of the top substrate . • the top substrate and the base substrate are arranged with defined distance relative to each other and define a cavity , wherein a first frequency band is basically defined by the dimension of the top substrate , in particular of the top and the base substrate , and in particular by the defined distance, • the top substrate comprises a set of at least four slots (14a-d,44), wherein a second frequency band basically is defined by the design and arrangement of the at least four slots (14a-d,44), the second frequency band is different from the first frequency band , • the cavity is designed so that for the first and the second frequency band the monopole antenna has preferred monopole sending and/or receiving directions substantially parallel to the extension of the substrates, in particular horizontally, • the top substrate is configured to provide a basis for attaching an additional sending and/or receiving unit which provides a preferred sending and/or receiving direction substantially orthogonal to the preferred monopole sending and/or receiving directions, and to provide a ground plane for the additional sending and/or receiving unit, • wherein the set of at least four slots (14a-d,44) are arranged in an adjacent manner so that a size and a shape of the ground plane is defined by the slots, and • the antenna assembly comprises a feed configured to transmit signals to and/or from the additional sending and/or receiving unit, wherein the feed is designed as a feeding pin protruding from the base substrate and extending to the bottom side of the top substrate in the region of the ground plane , <EOS>