In-Orbit Calibration of Phased Array Antennas Using GNSS Carrier-Phase Measurements

This paper proposes a passive in-orbit calibration method for phased array antennas using GNSS carrier-phase measurements. By performing synchronous observation and exploiting the short-baseline property between the positioning antenna and array elements, the first differencing operation eliminates space propagation errors and clock biases. By further utilizing receiver channel consistency, the second differencing operation cancels out the receiver channel errors, thereby extracting the relative receive-chain phase error of the element under test. Under typical operating conditions, the calibration accuracy can reach an RMS error of approximately 3.02mm, corresponding to a phase accuracy of 5.72° in the GPS L1 band. This accuracy is close to the 5.625° minimum phase step of a 6-bit digital phase shifter, and can be further improved under higher C/N0 and well-controlled residual error conditions. Without requiring a dedicated GNSS band excitation signal, this method avoids co-frequency self-interference with the positioning antenna, which provides an auxiliary approach for in-orbit calibration of phased array receive chains.