A wireless handheld or portable device includes a communication module with a MIMO system that provides multiband MIMO operation in first and second frequency bands. The MIMO system includes first and second radiating systems, a ground plane common to the two radiating systems, first and second radio frequency systems, and a MIMO module. The first and second radiating systems both operate in the first and second frequency bands and respectively include first and second radiating structures coupled to the ground plane, which respectively have first and second radiation boosters that fit in an imaginary sphere having a diameter smaller than ¼ of a diameter of a radiansphere of a longest wavelength of the first frequency band. The first and second radiofrequency systems respectively modify impedance of the first and second radiating structures to provide impedance matching to the first and second radiating systems within the first and second frequency bands.