On 9 February 2002, VitaTech Engineering was contracted by a university
to design, install, test and certify a AC ELF EMI/RFI magnetic shield.
Between May 10th and May 13th 2002, VitaTech
installed a 9' x 12' x 8'(height) shield composed of conductive seam
welded aluminum plates and extruded aluminum I-Beams. Additionally, an
RF sealed
door and filtered penetrations for HVAC and signal cables were installed
to complete the design. Low (0.1-9.99 mG) AC ELF magnetic emissions
emanated into room #240 from 60 Hz sources inside the room and from the
electrical
closet located across the hallway. In addition, the high frequency
noise from multiple sources needed to be attenuated for the newly proposed
EEG
laboratory.
Site Survey
Before
Shield
Data Collected at Floor Level
Before
Shield
Data Collected at 1 Meter Level
Slideshow
BEFORE DATA:
Inside Shielded Area
5 Hz - 100 KHz
Electric Field
Er Range @ 1-m |
Inside Shielded Area
100 KHz -3 GHz
Electric Field
Er Range @ 1-m |
Inside Shielded Area
60 Hz
Magnetic Field
Br Range @ 1-m |
| Min: 0.158 V/m |
Min: 0.000 V/m |
Min: 0.1 mG |
| Max: 0.825 V/m |
Max: 3.200 V/m |
Max: 2.64 mG |
| Mean: 0.274 V/m |
Mean: 1.112 V/m |
Mean: 0.46 mG |
AFTER DATA:
Inside Shielded Area
5 Hz - 100 KHz
Electric Field
Er Range @ 1-m |
Inside Shielded Area
100 KHz -3 GHz
Electric Field
Er Range @ 1-m |
Inside Shielded Area
60 Hz
Magnetic Field
Br Range @ 1-m |
| Min: 0.000 V/m |
Min: 0.000 V/m |
Min: 0.0 mG |
| Max: 0.000 V/m |
Max: 0.000 V/m |
Max: 0.0 mG |
| Mean: 0.000 V/m |
Mean: 0.000 V/m |
Mean: 0.0 mG |
