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 Author Topic: RF SHIELDING BY WIRE GRIDS (MESH)  (Read 14466 times) 0 Members and 1 Guest are viewing this topic. Click to toggle author information(expand message area).
ANDREAKIS
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 « Embed this message on: September 13, 2008, 04:48:13 pm »

RF SHIELDING BY WIRE GRIDS (MESH)

How  can I  estimate  the  attenuation (in dB)  induced  to  a vertically  polarized  planar  wave ,  f=100 MHz ,  incident on

a  large, conducting wire-grid  (mesh)  consisting  of: vertical  wires of  diameter (d) each ,  spaced  apart  by  distance  D ?? (D counts from wire axis to wire axis )

Can  we  get  an  approximate  mathematical  formula for  various d,D and f ??  No  simulation  requested !

The  grid  also  contains  horizontal  wires, equally  spaced  by  distance D1 . Will  this make any  difference in vertical polarized  waves ??

BEST REGARDS
ELIAS / ATHENS / GREECE

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Fu-Kwun Hwang
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 « Embed this message Reply #1 on: September 13, 2008, 09:20:45 pm »

Frequency f=100MHz, so the wavelength= 3*108/108=3M
I believe the distance D between your conducting wire grid is much small than the wavelength.
I will assume the wire can behavior like a conducting plate. So I think it can stop most of the electromangetic field if those wire are very good conductors.
However, if the distance D become larger , than I do not think there is a simple formula available.

Are you doing some real project or this is just some test problem?
What is the source for your 100MHz vertically polarized electromagnetic wave?
What is the spatial distribution of the EM wave?
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p.richard
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 « Embed this message Reply #2 on: September 13, 2008, 09:53:03 pm »

pls. i want a lecture note on the use of the mirror formular
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Fu-Kwun Hwang
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 « Embed this message Reply #3 on: September 13, 2008, 10:17:53 pm »

You were asking about attenuation. And you change the subject to mirror formula?
What do you mean by mirror formula? I do not understand your question?
Please write down in detail what you were doing and what you plan to do ?
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ANDREAKIS
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 « Embed this message Reply #4 on: September 14, 2008, 01:31:16 pm »

Frequency f=100MHz, so the wavelength= 3*108/108=3M
I believe the distance D between your conducting wire grid is much small than the wavelength.
I will assume the wire can behavior like a conducting plate. So I think it can stop most of the electromangetic field if those wire are very good conductors.
However, if the distance D become larger , than I do not think there is a simple formula available.

Are you doing some real project or this is just some test problem?
What is the source for your 100MHz vertically polarized electromagnetic wave?
What is the spatial distribution of the EM wave?

Dear Fu ,

What I  want is to  shield  a large window from  incident FM  radiation. So ,I  would  like to  select ,from the  market , a suitable  wire - grid . Of course the dimensions d and D will be much smaller compared to wave - length . I would  like however ,to have a mathematical  formula on the attenuation that  will  be  achieved (in dB) to chose the  right  grid.
The EM-wave spatial  distribution can be  assumed uniform .
Are  there any lecture notes  related  to  the  subject ?? I would be  interested .

Best Regards
Elias

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Fu-Kwun Hwang
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 « Embed this message Reply #5 on: September 14, 2008, 04:21:02 pm »

How large is the space you would like normal F.M. signal to be shield?
I do not know there is a equation related to metal wire grid.
May be there are some papers about it. But I do not know.
Do you really need to know the equation? What is the requirement for your shielding?
You can check out text book for electromagnetic wave to find related information.
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Life well spent is long. ..."da Vinci (1452-1519, Italian artist, sculptor, painter, architect, engineer and scientist) "