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3.2.1 Direct radiation from trace and IC package loops on the PCB

According to [58] the estimation for the maximum radiated electric far field density from a loop current Idm on a PCB as depicted in Figure 3.1 is

$\displaystyle E_{max}(f)\approx\left(2.6\cdot10^{-14}\frac{Vs^2}{Am^2}\right)\cdot\frac{I_{dm}(f)A}{r}f^2,$ (3.1)

where A is the loop area, r is the distance of the field observation point from the loop and Idm is the magnitude of the harmonic at frequency f of the loop current Idm. The current Idm can be obtained from standard time domain network simulation and FFT. Note that this is a first order estimation, intended to classify the direct radiation of PCB loops regarding their ability to exceed an emission limit. This estimation considers neither the influence of shields on the PCB, nor the influence of an enclosure.
Figure 3.1: Radiating current loop on a PCB.
\includegraphics[height=4 cm,viewport=70 590 540 720,clip]{pics/Abstrahlung_Schleife.eps}


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C. Poschalko: The Simulation of Emission from Printed Circuit Boards under a Metallic Cover