Physical approach of EMC testing methods - Overview and description

Electromagnetic compatibility metrology, succinctly referred to as "EMC metrology", covers such a varied field of application that it would be illusory to detail its content in the space of a single article. For these reasons, the author has decided to limit his presentation to the evaluation of the electromagnetic emission or immunity of an electronic device, and to the measurement of radiofrequency waves carrying weak or strong fields.

In terms of official terminology, emission refers to undesirable electromagnetic fields radiated at a distance from a device and capable of causing interference that could alter the operation of a neighboring device.

Conversely, a device's immunity characterizes its ability to function unaltered in the presence of electromagnetic fields of a frequency range and intensity predefined by a test protocol.

The subject will be developed in two distinct parts, comprising two articles linked by common physical properties.

The first part of the text, entitled "General description", covers the protocols for emission measurements and electromagnetic immunity tests, as well as the receiving antennas used for low-frequency measurements.

The second part of the article [R 935] is entitled "Analysis of phenomena", and aims to explain the contribution of the various physical factors acting on the scale of the main passive or active components making up the device under test.

Let's go back to the first part and briefly describe the first paragraph. First of all, we'll define what constitutes a device undergoing emission or immunity testing. The presentation will focus on the physical nature of the variables involved in EMC metrology, and then on the division of the spectrum into three frequency ranges: low frequencies from 150 kHz to 30 MHz, high frequencies from 100 MHz to 1 GHz, and intermediate frequencies bridging the gap from 30 MHz to 100 MHz. As we shall see from the examples, this division of the spectrum is not arbitrary, but is justified by the properties of broadband antennas and the nature of the variables required for measurement or testing. Measurement and test protocols generally used in semi-anechoic chambers will also be examined, to highlight various sources of uncertainty.

In the second section, we analyze the operation of receiver antennas used in some transmitter measurements between...