Compact calibration scheme for planar DBF transmit antenna arrays using circular polarization at Ka-band

A compact calibration scheme, especially suited for planar transmit antenna arrays using digital beamforming (DBF) and circular polarization, is presented. This scheme relies on an online differential measurement of a section of the antenna element radiation pattern by use of external probe antennas. The paper focuses on extraction of calibration data and the design and test of suitable probe antennas. Measurement results are presented for the probe antennas and simulation results for the accuracy of the calibration scheme.