A novel on-orbit calibration technique for large phased array antenna

Large APAA (active phased array antenna) contains hundreds of elements and the performance of an APAA will degrade over time as a result of changes mainly in the solid-state components. For airborne and satellite-borne APAA applications, ground-based calibration sources may be difficult or impractical to implement due to the constraints of volume and resources. In this paper, a novel self-calibration technique is proposed in order to measure the amplitude and phase degradation of each active array element. By fast and accurate measurement with little satellite resource cost, this technique can be easily applied to the on-orbit diagnostics and self-calibration for APAA. The technique presented in this paper takes the advantages of APAA properties that the attenuator and phase-shifter in each element module can be controlled flexibly while operating on-orbit measurements. The dedicated internal passive calibration elements are employed in array aperture to measure the complex electric fields between each other active array elements. During the process of measurement, one active element needs to be rotated in three phase intervals, while other non-rotating active elements set to the maximum attenuation. Then this process is repeated for every active element to work out the phase and amplitude distribution of array aperture. The calculation results shown in this paper match the requirements of amplitude and phase measurement accuracy for an on-orbit phased array self-calibration.