Calibrartion
The STEREO/WAVES experiment (SWAVES) onboard the two STEREO spacecraft are equipped with three orthogonal monopole antennae, each 6 meters long. For the evaluation of the SWAVES data the receiving properties of the antennae (effective length vector), influenced by the spacecraft body, have to be accurately known.
An in-flight calibration of the effective length vectors of the antennae was performed using the observations of the terrestrial auroral kilometric radiation (AKR) in an early stage of the mission when the spacecraft, still close enough to Earth, performed a series of roll manoeuvres (Fig. 1). A special least squares method combined with a specifically adapted genetic algorithm was applied to find the effective length vectors which best fit the physical model describing the reception scenario on the basis of the observations (Fig.2).
The results are very accurate and are recommended as a basis for future evaluations of SWAVES data. They confirm the former SWAVES antenna analysis by rheometry and numerical simulations, particularly verifying the importance of mutual antenna capacitances in the application of these methods.
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