Radio detection of extensive air showers at the Pierre Auger Observatory

Cosmic rays interact with the Earth's atmosphere developing extensive air showers (EAS). The EAS can be measured not only using particle detectors on the ground, but also using radio antennas. The radio emission of EAS covers a wide frequency range from the MHz up to the GHz range. Recently, several experimental activities at the Pierre Auger Observatory have measured the radio emission of EAS in the microwave (EASIER, MIDAS, AMBER) and MHz ranges (AERA). The Auger Engineering Radio Array and similar experiments showed that emission in the MHz range has two contributions: the time-varying transverse currents of geomagnetic origin and the time-varying charge excess. The measurements of Cosmic-Ray Observation via Microwave Emission (CROME) could be well described by this formalism established in the MHz range and extended to GHz. In this talk, the radio emission of EAS in the MHz and GHz ranges and the experimental setups at the Pierre Auger Observatory are discussed.