Radiation patterns of a large UHF phased-array antenna: a comparison of measurements using satellite repeaters and patterns derived from measurements of antenna current distributions

The radiation patterns of a 404-MHz phased-array-radar antenna were measured relative to a reference dipole antenna, using 406-MHz repeaters on polar-orbiting satellites and associated ground-station equipment. More than 6000 measurements were collected from the three radar-antenna beams over a five-month period in 1995. The patterns were compared with those derived from measurements of the complex current distributions on the coaxial collinear radiating elements of the antenna. In addition to verifying the antenna specifications for gain, beamwidth, pointing direction, and sidelobe levels, the far-field satellite repeater measurements validated the convenient and inexpensive current measurement and model technique, developed for antenna testing and maintenance.