Calibration and Measurement Methods for Phased Array Beamforming Antennas

Beamforming antennas require precise alignment of the individual radiator elements to provide accurate beamforming with low sidelobes. For transmitters, accurate measurement of Effective Isotropic Radiated Power (EIRP), as well as beam pattern is critical. Further, modern antennas may be just for both sensing and communications (Joint Communications and Sensing, or JCAS), so that they must operate with good linearity when used for communication but with high efficiency for sensing. For receive-antennas, the same beamforming requirements apply, with the additional requirement of characterizing the noise characteristics (typically called Gain/Temperature or G/T). Finally, the radiator count for these antennas is increasing with 1000 or 2000, or more, being considered. This presentation will discuss state-of-the-art methods for testing transmitter and receiver antenna characteristics as well as high-speed phased array element calibration. The focus will be for the case of a Compact Antenna Test Range (CATR) which reduces the size and complexity of the test system. In particular, we will discuss the calibration methods to remove effects of cabling, feed-horn characteristics and range loss to create a precise test environment, as well as extending the antenna test capabilities to include modulation quality (EVM) and noise figure (G/T).