BEAMFORMING FOR CIRCULAR AND SEMICIRCULAR ARRAY ANTENNAS FOR LOW-COSTWIRELESS LAN DATA COMMUNICATIONS-SYSTEMS

An investigation into beam synthesis for small circular and semicircul ar arrays is presented. Array antennas of this type are likely to beco me a core component in future wireless LAN systems architecture. They offer additional spatial diversity as a means for combating multipath interference, necessary for high speed data communications, and user m obility. Beams are synthesised using cophasal and adaptive algorithms. Beamwidths of 19 degrees and -20dB sidelobe levels are attainable fro m an array of three wavelengths diameter. A semicircular array of this type can maintain a gain of approximately 10 dBi over a look directio n angular range of +/-50 degrees.