Mills Cross Telescope

The Mills Cross Telescope was a two-dimensional radio telescope built by Bernard Mills in 1954 at the Fleurs field station of the Australian Commonwealth Scientific and Industrial Research Organisation in the area known now as Badgerys Creek, about 40 km west of Sydney, New South Wales, Australia.

Each arm of the cross was 1500 feet (450 m) long, running N–S and E–W, and produced a fan beam in the sky. Mills said it "consists of two rows of 250 half-wave dipole elements backed by a plane wire mesh reflector; the individual dipoles are aligned in an E-W direction." The cross operated at a frequency of 85.5 MHz (3.5m wavelength), giving a 49 arcminute beam.

When the voltages of the two arms were multiplied a pencil beam was formed, but with rather high sidelobes. The beam could be steered in the sky by adjusting the phasing of the elements in each arm.