A wireless handheld or portable device capable of multiband MIMO operation comprising a communication module including at least one MIMO system, wherein the at least one MIMO system comprises at least two radiating systems capable of transmitting and receiving electromagnetic wave signals, wherein at least two of the radiating systems are capable of transmitting and receiving electromagnetic wave signals in at least a first frequency band, and wherein at least two of the radiating systems are capable of transmitting and receiving electromagnetic wave signals in at least a second frequency band. The MIMO system further comprises a MIMO module arranged for processing the electromagnetic wave signals. At least one of the radiating systems includes a radiating structure comprising a ground plane (157) capable of supporting at least one radiation mode, and a radiation booster (151a-b, 152, 153) arranged to couple electromagnetic energy from/to the ground plane.