A comprehensive overview of the newly developed EVA-code is given. To take into account Cherenkov effects and include realistic showers in combination with shower-to-shower fluctuations we have developed the EVA code (Electric fields, using a Variable
index of refraction in Air shower simulations code). The EVA-code is based on histograms obtained from a full Monte-Carlo CONEX simulation to calculate radio emission from cosmic-ray-induced air showers. The EVA-code makes use of the finite dimensions of the particle distributions to overcome the divergences in the fields due to Cherenkov effects without making any approximations.