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Angled dipole in rotatable frame for evaluating shielding effectiveness of enclosures

IP.com Disclosure Number: IPCOM000029269D
Original Publication Date: 2004-Jun-21
Included in the Prior Art Database: 2004-Jun-21
Document File: 4 page(s) / 79K

Publishing Venue

IBM

Abstract

The apparatus described is used in a method of performing shielding effectiveness (SE) tests on various equipment enclosures for the purpose of evaluating the effectiveness of an enclosure to contain radiated electrical or magnetic noise

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Angled dipole in rotatable frame for evaluating shielding effectiveness of enclosures

Problem is effective determination of shielding effectiveness (SE) for enclosed electronic products. Method now is using battery-powered radiators. Problems are polarization determination, battery rundown, and precise amplitude level control.

     This invention involves setting a broadband dipole at an angle within an enclosure and effectively rotating the enclosure about the stationary dipole to determine the SE at all azimuths. The dipole at an angle allows the determination of a SE response to horizontal and vertical polarization (with a 3dB correction). An overall view of the invention is shown in Figure 1. It consists of a bottom square stationary plate (blue) and a round plate (grey) with a vertical shaft (grey).

FIGURE 1

1

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     At the top of the shaft is mounted a broadband dipole antenna (changeable to other sizes and types) to obtain a higher frequency range or directivity (see Figure 2). The connecting cable (red) can be coaxial, triaxial, or twinaxial cable that extends through the length out the bottom of the plates for connection to a signal generator.

FIGURE 2

     The sleeve surrounding the cable (blue) extends through the outside vertical shaft (grey) and is connected at the ends through bushings or bearings (violet). so that it can rotate within the outer vertical shaft. Figure 3 shows the bottom side of th...