From 1954 to 1963, CSIRO’s Fleurs field station was one of the world’s leading radio astronomy observatories. The Mills Cross, named for its designer, Bernie Mills, consisted of 450m-long north-south and east-west arrays of dipole antennas. Each arm consisted of two rows of 250 half-wave dipole elements backed by a plane wire-mesh reflector. The Cross operated at a frequency of 85.5 MHz (a wavelength of 3.5m), giving a 49 arcminute beam. The image above shows Alex Little and Bernie Mills making some calibration tests of the Cross elements. (Image credit: CSIRO Radio Astronomy Image Archive )