RFI
Shielding Performance for Display & Window
The EmiClare™ RFI shielding display provides exceptional optical performance without
sacrificing RFI shielding characteristics.
The
unique EmiClare rfi shielding mesh configuration eliminates the
complexity of wire types, mesh counts and plated finishes
found in conventional windows.
This data sheet gives you the means to estimate the Emi, rfi
shielding performance of an EmiClare window. The data is
based on an extensive development programme followed by
testing in accredited test houses in the USA and England.
The
attenuation properties of the emi/rfi shielding medium
three
factors determine the EMI shielding effectiveness of a
window:
1. The attenuation properties of the shielding medium
2. The shadow effect of the aperture
3. The efficiency of the termination
Termination
Efficiency
The
most efficient termination is the direct contact of the
mesh to the bezel / enclosure via a mesh extension. Data
for two standard EmiClare terminations are listed below:
| Silver
busbar |
100
MHz - 10GHz |
10dB
loss |
| Silver
busbar and conductive gasket |
100
MHz - 3GHz |
10
dB loss |
| 4
GHz - 10 GHz |
0
dB loss |
| (Chomerics
Softshield 5000) |
Between
10 and 100 MHz Visiontek Systems Ltd has found that
traditional terminations, with a silver busbar contacting
the cross section of the wire, are ineffective. We advise
that the window uses one of the extended mesh
terminations.
Aperture
Shadow Effect
In
cases where the emission levels are known, the shadow
effect of the aperture can be estimated from the nomograph
and added to the mesh attenuation with allowance for the
termination:
| EXAMPLE |
|
| Opening
Size: |
250
x 200 mm |
| Max.
dimension is diagonal |
320mm |
| Frequency
MHz |
1.0 |
5.0 |
10 |
50 |
100 |
500 |
1000 |
| Aperture
Attn dB |
53 |
39 |
33 |
19 |
13 |
0 |
0 |
| Mesh
Attn dB |
70 |
70 |
70 |
58 |
73 |
60 |
53 |
| Silver
Busbar dB |
-10 |
-10 |
-10 |
-10 |
-10 |
-10 |
-10 |
|
| Overall
Attn dB |
113 |
99 |
93 |
67 |
76 |
50 |
43 |
|