A design of radio interferometer consisting of numerous antennas arranged in two arms in the form of a cross oriented north–south and east–west. It can be configured to produce either a pencil beam or a fan beam. The original Mills Cross, in Sydney, had 500 half-wave dipoles placed along two arms 457 m long. The Mills cross is named after its designer, the Australian radio astronomer Bernard Yarnton Mills (1920–2011).