Calibration of standard gain antennas using a spherical near-field technique

The calibration of standard gain antennas using a spherical near-field range and pattern integration is investigated. A combination of measurements and analytical methods is used to obtain the absolute gain, and accurate results for peak directivity are yielded by the pattern measurements in the near field transformed to the far field. The absolute gain can then be calculated knowing the insertion loss of the antenna. A value for the insertion loss of the antenna is analytically obtained, and the reflection coefficient is determined by a slotted line technique carried out on a test bench in an anechoic environment. The polarization properties of the antennas are then determined by a separate measurement in the radio anechoic chamber. The results show that correction for proximity effects as well as the directive properties of the measuring antennas have a significant effect on the accuracy of the calibration, even at distances greater than the Rayleigh distance.