  The Auger Engineering Radio Array (AERA) aims at the detection of air showers
induced by high-energy cosmic rays. As an extension of the Pierre Auger
Observatory, it measures complementary information to the particle detectors,
fluorescence telescopes and to the muon scintillators of the Auger Muons and
Infill for the Ground Array (AMIGA). AERA is sensitive to all fundamental
parameters of an extensive air shower such as the arrival direction, energy and
depth of shower maximum. Since the radio emission is induced purely by the
electromagnetic component of the shower, in combination with the AMIGA muon
counters, AERA is perfect for separate measurements of the electrons and muons
in the shower, if combined with a muon counting detector like AMIGA. In
addition to the depth of the shower maximum, the ratio of the electron and muon
number serves as a measure of the primary particle mass.
