An investigation on radiated emissions from heatsinks

With the increase in processor speed the power dissipation density of high speed asics are increasing. The most common method of dissipating the power produced in an asic is by using a heatsink. However, due to its close proximity to the high speed digital processor a heatsink also acts as an antenna. The radiating efficiency of the heatsink depends on its shape and clock frequency of the exciting asic. Quite often the energy radiated by a heatsink gets coupled to internal cables or nearby slots inside a computer enclosure. The cables and slots then emits the energy outside the box. The objective of this study was to investigate the radiated emissions from heatsinks. In this article, radiated emissions from a circular heatsink was investigated. The heatsink has been compared to a monopole. The radiated emission has been measured in a semi-anechoic chamber and numerically simulated.