Embodiments of the invention relate to 
beamforming antennas such as can be used in 
space division multiplexing systems. 
Space division multiplexing can be used to increase 
data capacity in 
wireless networks by enabling different base stations to transmit signals within the same 
frequency band. Each antenna beam can potentially be used to establish a 
communication link within an area of 
wireless coverage, and other communication links established on other antenna beams then represent interference to that user. In order to reduce interference, narrow beamwidths are desirable. These are typically achieved by increasing the aperture of the antenna in the 
azimuth plane, and in arrangements that require finely divided angular sectors, a greater number of antennas will be required to give three hundred and sixty degree coverage. As a result, there is potentially a large increase in the total surface area of antennas which is undesirable, as it leads to increased wind loading of an antenna 
tower. Embodiments of the invention provide an arrangement in which data are transmitted from a first 
transmitter to a first 
receiver using a first antenna beam, and data are transmitted from a second 
transmitter to a second 
receiver using a second antenna beam. The first antenna beam is formed by splitting the 
signal from the first 
transmitter into two parts with a first 
phase relationship between the parts, each part being connected to an antenna. A second antenna beam is formed by splitting the 
signal from the second transmitter into two parts with a second 
phase relationship between the parts, each part being connected to one of the two antennas. An 
advantage of embodiments of the invention is that data can be transmitted from different transmitters at the same frequency without interference, while presenting a smaller 
antenna aperture than is required with conventional systems.