61000-4-20

The 61000-4-20 is the standard for the Tem cells

Emission

The Tem cell is a different and cost efficient method, compared to the OATS, to measure the emission patron of the EUT. This method does have a down side, calculation is needed to correlate the measurements done in the Tem cell to the OATS

For the emission there are 2 ways of calculation:

1. multi pole model
2. three voltage measurements

With the correlation the assumption is that under far field conditions the emitted power

Multi pole model

The multi pole model is currently not supported by RadiMation^®

Voltage measurements: 3-Positions

Also known as the "To Radiated Power method". In this method the EUT is placed in 3 axis (x,y,z).

$S={\sqrt {V_{x}^{2}+V_{y}^{2}+V_{z}^{2}}}$

$V_{x}$, $V_{y}$ and $V_{z}$ are the measurements done in Volt on the same frequency but in different directions.

$S$ is the Root-sum-square of the measured voltages.

$E_{max}=G_{max}*{\sqrt {{\frac {3\eta _{0}}{4\pi }}P_{0}}}$

$E_{max}$ is the maximum field in V/m

$\eta _{0}={\sqrt {\frac {\mu _{0}}{\epsilon _{0}}}}=120\pi \Omega =377\Omega$

$G_{max}$ is the geometry factor determined by the height scan of the receiving antenna.

Equipment Under Test

The ability of an EUT to be immune to incoming electromagnetic interference. This is equivalent to the term susceptibility that is used by some standards.