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Method of RF Anechoic or Semi-anechoic Chamber Construction

IP.com Disclosure Number: IPCOM000110510D
Original Publication Date: 1992-Dec-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Fujio, S: AUTHOR [+3]

Abstract

Disclosed is an RF absorber arrangement method to optimize the performance of RF anechoic or semi-anechoic chamber specifically designed for electromagnetic interference (EMI) measurement. The absorption characteristic of the RF absorber is a function of incident angle between the RF absorber and the electromagnetic wave. This method predicts the incident angle from the dimension of the chamber and measurement distance and arranges RF absorber placement so that best absorber performance is utilized.

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Method of RF Anechoic or Semi-anechoic Chamber Construction

       Disclosed is an RF absorber arrangement method to
optimize the performance of RF anechoic or semi-anechoic chamber
specifically designed for electromagnetic interference (EMI)
measurement.  The absorption characteristic of the RF absorber is a
function of incident angle between the RF absorber and the
electromagnetic wave.  This method predicts the incident angle from
the dimension of the chamber and measurement distance and arranges RF
absorber placement so that best absorber performance is utilized.

      RF anechoic or semi-anechoic chamber is a facility that
simulates an electromagnetic environment of free space or free space
with metallic ground plane.  The RF anechoic or semi-anechoic chamber
consists of shielded enclosure 1 and RF absorber 2 attached to the
inside wall of the enclosure, as shown in Fig. 1.  The RF absorber
absorbs electromagnetic wave energy and reduces reflection at the
shielded enclosure as if there is no enclosure.  Therefore, the
smaller the electromagnetic wave reflection at wall, the better the
performance of the chamber.  The RF absorber performance varies with
respect to the incident angle of electromagnetic wave to the RF
absorber, and the best performance is obtained when the incident
angle is a right angle.  The incident angle 3 is depicted in Fig. 2.

      Recent measurement standards that regulate EMI use measurement
distance of 3 m or 10 m.  Theref...