  The stellar wind in high-mass microquasars should interact with the jet. This
interaction, coupled with orbital motion, is expected to make the jet follow a
helical, nonballistic trajectory. The jet energy dissipated by this
interaction, through shocks for example, could lead to nonthermal activity on
scales significantly larger than the system size. We calculate the broadband
emission from a jet affected by the impact of the stellar wind and orbital
motion in a high-mass microquasar. We employ a prescription for the helical
trajectory of a jet in a system with a circular orbit. Subsequently, assuming
electron acceleration at the onset of the helical jet region, we compute the
spatial and energy distribution of these electrons, and their synchrotron and
inverse Compton emission including gamma-ray absorption effects. For typical
source parameters, significant radio, X- and gamma-ray luminosities are
predicted. The scales on which the emission is produced may reduce, but not
erase, orbital variability of the inverse Compton emission. The wind and
orbital effects on the radio emission morphology could be studied using very
long baseline interferometric techniques. We predict significant broadband
emission, modulated by orbital motion, from a helical jet in a high-mass
microquasar. This emission may be hard to disentangle from radiation of the
binary itself, although the light curve features, extended radio emission, and
a moderate opacity to very high-energy gamma rays, could help to identify the
contribution from an extended (helical) jet region.
