Wireless Network System and Devices

A wireless network device (4), such as a wireless media centre, has orthogonally polarised antennas (6a, 6b) arranged to provide transmit and/or receive polarisation diversity. The antennas may be arranged so that their nulls do not coincide, to produce a combined antenna pattern with a low variation of gain with direction. The antennas may be collocated, but arranged orthogonally. Preferably, the combined antenna pattern is substantially omnidirectional in elevation as well as azimuth. This arrangement provides uniform coverage in a 3D environment. The transmitter may transmit data using polarisation-time block codes. A wireless receiver (10, 18) for use in the wireless network may have either one antenna or two orthogonally polarised antennas. The receiver (10, 18) applies maximal ratio combining to the received signals. The signals may be OFDM signals and the receiver applies maximal ratio combining independently to each frequency channel. The antennas may be flat linear or annular slot antennas, which provide strongly polarised beams and can be integrated within the housing of the devices.