A planet orbiting around a pulsar would be immersed in an ultra-relativistic under-dense plasma flow. It would behave as a unipolar inductor, with a significant potential drop along the planet. As for Io in Jupiter’s magnetosphere, there would be two stationary Alfv´en waves, the Alfv´en wings (AW), attached to the planet. The AW would be supported by strong electric currents, in some circumstances comparable to those of a pulsar. It would be a cause of powerful radio waves emitted all along the AW, and highly collimated through relativistic aberration. There would be a chance to detect these radio-emissions from Earth. The emission would be pulses as for ordinary pulsars; their occurrence would depend on the planet-star-observer angle. These results are still preliminary, further work needs to be done.