  The STEREO/WAVES (SWAVES) experiment on board the two STEREO spacecraft
(Solar Terrestrial Relations Observatory) launched on 25 October 2006 is
dedicated to the measurement of the radio spectrum at frequencies between a few
kilohertz and 16 MHz. The SWAVES antenna system consists of 6 m long orthogonal
monopoles designed to measure the electric component of the radio waves. With
this configuration direction finding of radio sources and polarimetry (analysis
of the polarization state) of incident radio waves is possible. For the
evaluation of the SWAVES data the receiving properties of the antennas,
distorted by the radiation coupling with the spacecraft body and other onboard
devices, have to be known accurately. In the present context, these properties
are described by the antenna effective length vectors. We present the results
of an in-flight calibration of the SWAVES antennas using the observations of
the nonthermal terrestrial auroral kilometric radiation (AKR) during STEREO
roll maneuvers in an early stage of the mission. A least squares method
combined with a genetic algorithm was applied to find the effective length
vectors of the STEREO Behind (STEREO-B)/WAVES antennas in a quasi-static
frequency range ($L_{antenna} \ll \lambda_{wave}$) which fit best to the model
and observed AKR intensity profiles. The obtained results confirm the former
SWAVES antenna analysis by rheometry and numerical simulations. A final set of
antenna parameters is recommended as a basis for evaluations of the SWAVES
data.
