Multiple input multiple output (MIMO) systems are able to provide wireless communications at increased data rates. These systems involve using a plurality of antennas on both the transmitter and receiver and the problem of how to accommodate such structures in user terminals, which are often required to be hand held then arises. An antenna arrangement which is suitable for MIMO communications and which can be incorporated into a user terminal such as a personal digital assistant (PDA) is described. A pair of co-polarised umbrella monopoles and a slot antenna are incorporated into a flap which extends at approximately 90.degree. to the body of the PDA. A fourth monopole is mounted and protrudes from the PDA itself.