A Study on the Radiation Characteristics of Microelectronic Probes

Microelectronic probes with the ground-signal-ground (GSG) tips have been widely used in testing integrated circuits and antennas. Yet, the radiation from probes has been rarely studied, which has been found to degrade the testing accuracy of the radiation from an antenna. In this paper, a typical ACP40-GSG-100 probe is studied from both simulation and measurement. It is confirmed that the probe radiation is caused by current on its tips, the metal probe shell strongly affects the radiated power distribution, and the ignorance of probe radiation causes error to the realized gain calculation. It is found that the probe shows a symmetrical radiation pattern for its symmetrical current distribution on the tips, the matched probe has larger realized gain than the open-ended one for about 4.8 dB because of stronger current, and the different contact positions on an impedance standard substrate (ISS) make the radiation distribution be different but hardly affect the realized gain. The strongest radiation of the probe basically locates within a narrow region near the symmetry plane of the probe, which makes it easier and faster to find the peak gain. A simple mathematical model is given to explain why low-gain probes are preferred in antenna radiation tests.