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Browse Prior Art Database

Electromagnetic Interference Measurement Tool for Near to Far Field Correlation

IP.com Disclosure Number: IPCOM000037172D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Soohoo, KM: AUTHOR [+2]

Abstract

The electromagnetic interference (EMI) measurement tool provides a way to control the EMI boundary conditions around any data processing equipment (computer systems, etc.) under test and thus enables on-site (in-situ) measurement to be done anywhere with a high degree of correlation to free field (ideal) facility test results.

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Electromagnetic Interference Measurement Tool for Near to Far Field Correlation

The electromagnetic interference (EMI) measurement tool provides a way to control the EMI boundary conditions around any data processing equipment (computer systems, etc.) under test and thus enables on-site (in-situ) measurement to be done anywhere with a high degree of correlation to free field (ideal) facility test results.

The tool is comprised of an electrically continuous flexible metallic shell placing over the EUT (Equipment Under Test). The shell can be any geometric shape (cylindrical, cubical, etc.) and is suspended over the EUT in a fixed orientation. Metallic wire mesh or foil can be used to fabricate the shell; the edge(s) of the shell is terminated at the raised metal floor or ground plane in 360- degree manner (capacitive coupled or direct grounding).

To find the radiation potential of the EUT inside the shell, a controlled aperture (vertical, horizontal or 45-degree cross polarized) is made on the shell to allow EMI leakage. Localized electric and/or magnetic probe(s) can be used to quantify the EMI level. By controlling the length of the aperture one can then collect EMI data over various frequency ranges.

In order to provide far field correlation, another set of EMI data must be taken with the EUT in the free field facility. Once the near and far field data becomes available, a set of correlation factors can then be derived and any subsequent in- situ measurement wi...