TEM-cell Measurements of the Radiated Emissions from PCBs with Modal Reservation before and after Failure

In this paper, the levels of radiated emissions from printed circuit boards with modal reservation are estimated before and after failures. Four board prototypes (without modal reservation, and with modal reservation before and after short and open circuit failures) were manufactured to experimentally study their features. A laboratory model of a miniature TEM-cell was used to measure the frequency dependences up to 5 GHz of the voltage amplitude levels at its central conductor for all boards. The measured results obtained after failures were compared to those obtained before them. It was revealed that in general the level of radiated emissions for the board with modal reservation is lower than for the board without it even after failures, except at some frequencies of the studied domain, due to the frequency shifting. The study confirms experimentally the possibility of using the modal reservation layout and tracing approach for both improving the reliability and ensuring electromagnetic compatibility, in terms of not only the conductive emissions but also the radiated ones.