Radio emission of energetic cosmic ray air showers: Polarization measurements with LOPES

Abstract LOPES is a radio antenna array co-located with the Karlsruhe Shower Core and Array DEtector, KASCADE–Grande in Forschungszentrum Karlsruhe, Germany, which provides well-calibrated trigger information and air shower parameters for primary energies up to 10 18 eV . By the end of 2006, the radio antennas were re-configured to perform polarization measurements of the radio signal of cosmic ray air showers, recording in the same time both, the East–West and North–South polarization directions of the radio emission. The main goal of these measurements is to reconstruct the polarization characteristics of the emitted signal. This will allow a detailed comparison with theoretical predictions. The current status of these measurements is reported here.