High-velocity impacts of interplanetary dust grains with spacecraft can give rise to transient plasma clouds from the spacecraft bodies. It is believed these plasma clouds can affect spacecraft instruments. Laboratory results are presented demonstrating the interaction of small expanding plasma clouds with a simple antenna. Results corroborate the hypothesized origin of anomalous impulsive voltage signals recorded by Voyager 1 and 2 spacecraft during flybys of Saturn, Uranus, and Neptune, the International Cometary Explorer (ICE) during its flyby of comet Giacobini-Zinner, and Vega during its flyby of comet Halley. Results suggest that preflight calibration of antenna-plasma interactions may extend the range of spacecraft diagnostics. ¿American Geophysical Union 1995