Over the years, significant efforts have been devoted to the understanding of the radio emission of extensive air shower (EAS) in the range [20-250] MHz. Despite some studies led until the eighties, the [1-10] MHz band has remained unused for 20 years. However, it has been measured by these pioneering experiments and suggested by theoretical calculations that EAS emit a strong electric field in this band and that there is evidence of a large increase in the amplitude of the radio pulse with lower frequencies. The EXTASIS project, located within the radio astronomy observatory of Nançay and supported by the CODALEMA instrument, aims to study the [1-10] MHz band, and especially the so-called "Sudden Death" contribution, the expected radiation electric field created by the particles that are stopped upon arrival to the ground. We present our instrumental setup, the objectives of the EXTASIS project and our first results.