EMI Shielding Performance
EmiClare™ windows provide exceptional optical performance without sacrificing EMI shielding characteristics.
The unique EmiClare 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 Optical filters 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
|
|
