  In this work we present a new jet model for the non-thermal broadband
emission of low-mass microquasars. We calculate the contribution of
relativistic particles, primary electrons and protons as well as secondary
muons, charged pions and electron-positron pairs, to the electromagnetic
spectrum of the sources. The distribution in energy of all particle species is
obtained for an extended, inhomogeneous region. We include detailed analysis of
particle energy losses, injection, decay and escape from the acceleration zone.
We also calculate absorption effects due to photon-photon annihilation. As an
application, we consider the case of XTE J1118+480, a well-known low-mass X-ray
binary in the galactic halo, and we present predictions about its high-energy
radiation
