The calibration of an HF Radar used for ionospheric research

The HF radar on Bribie Island, Australia, uses crossed‐fan beams produced by crossed linear transmitter and receiver arrays of 10 elements each to simulate a pencil beam. The beam points vertically when all the array elements are in phase, and is steerable by up to 20° off vertical at the central one of the three operating frequencies. Phase and gain changes within the transmitters and receivers are compensated for by an automatic system of adjustment. The 10 transmitting antennae are, as nearly as possible, physically identical as are the 10 receiving antennae. Antenna calibration using high flying aircraft or satellites is not possible. A method is described for using the ionospheric reflections to measure the polar diagram and also to correct for errors in the direction of pointing.