  The lateral distribution function (LDF) for coherent electromagnetic
radiation from air showers initiated by ultra-high-energy cosmic rays is
calculated using a macroscopic description. A new expression is derived to
calculate the coherent radio pulse at small distances from the observer. It is
shown that for small distances to the shower axis the shape of the electric
pulse is determined by the `pancake' function, describing the longitudinal
distribution of charged particles within the shower front, while for large
distances the pulse is determined by the shower profile. This reflects in a
different scaling of the LDF at small and at large distances. As a first
application we calculate the LDF for proton- and iron-induced showers and we
show that this offers a very sensitive measure to discriminate between these
two. We show that due to interference between the geo-magnetic and the
charge-excess contributions the intensity pattern of the radiation is not
circular symmetric.
