Radio emission of extensive air showers is used to reconstruct prop-
erties of the ultra-high energy cosmic rays. With an area of 17 km$^2$, the Auger Radio Engineering Array has recorded a sizable number of cosmic rays with energies exceeding 1 EeV. Especially interesting are measurements of air showers
at large zenith angles because these induce sizable footprints recorded in
many radio stations. New challenges in reconstructing these showers
arise from the superposition of the two emission mechanisms leading
to the radio signal. We discuss the shower reconstruction with empha-
sis on the energy estimation where the aim is to provide an absolute
energy measurement of the primary cosmic ray exclusively from the recorded radio signal.