  Since 2003, significant efforts have been devoted to the understanding of the
radio emission of extensive air shower in the range [20-200] MHz. Despite some
studies led until the early nineties, the [1-10] MHz band has remained unused
for 20 years. However, it has been measured by some pioneering experiments that
extensive air shower emit a strong electric field in this band and that there
is evidence of a large increase in the amplitude of the radio pulse at lower
frequencies. The EXTASIS experiment, located within the Nan\c{c}ay
Radioastronomy Observatory and supported by the CODALEMA experiment, aims to
reinvestigate the [1-10] MHz band, and especially to study the so-called
"Sudden Death" contribution, the expected electric field emitted by shower
front when hitting the ground level. Currently, EXTASIS has confirmed some
results obtained by the pioneering experiments, and tends to bring explanations
to the other ones, for instance the role of the underlying atmospheric electric
field. Moreover, CODALEMA has demonstrated that in the most commonly used
frequency band ([20-80] MHz) the electric field profile of EAS can be well
sampled, and contains all the information needed for the reconstruction of EAS:
an automatic comparison between the SELFAS3 simulations and data has been
developed, allowing us to reconstruct in an almost real time the primary cosmic
ray characteristics.
