  In a recent analysis of the radio emission from the planetary nebula A30,
Dgani, Evans & White (1998) claim that the emission, located in the inner
region, is probably dominated by nonthermal emission.
  We propose a model to explain this.
  We assume that the fast wind, blown by the central star of A30 carries a very
weak magnetic field. The interaction of this wind with a cluster of dense
condensations traps the magnetic field lines for a long time and stretches
them, leading to a strong magnetic field.
  If relativistic particles are formed as the fast wind is shocked, then the
enhanced magnetic field will result in nonthermal radio emission.
  The typical nonthermal radio flux at 1 GHz can be up to several milli-Jansky.
  In order to detect the nonthermal emission, the emitting region should be
spatially resolved from the main optical nebula.
  We list other planetary nebulae which may possess nonthermal radio emission.
