Page 3 - EEC_EMI Tech Guide
P. 3
I/RFI
Shielded Enclosures from
System Equipto Electronics
Complex electronic systems often have an unwelcome side effect:
electro-magnetic and radio frequency interference (EMI/RFI).
More than just a nuisance, EMI/RFI can interfere with the opera-
tion of critical communication, computer and command and con-
trol systems.
As new equipment reaches higher and higher levels of perform-
ance and complexity, EMI/RFI can become a larger problem.
Packaging these types of electronic systems can be a difficult and
expensive design problem. Equipto Electronics has many years of
experience in the design and production of shielded enclosures
meeting requirements from commercial through military levels of
performance.
Equipto Electronics offers a wide variety of standard shielded
enclosures in many sizes. Since our shielded enclosures are based
on our proven Heavy Duty frame design, a wide variety of acces-
sories and options are available.
Shielded Enclosures-What’s important?
Shielding Performance EMI/RFI Cabinet Systems
Shielding performance is measured by attenuation. Attenuation is
the difference in signal strength between the inside and the out-
side of the enclosure and is measured in decibels (dB).
Attenuation characteristics of an enclosure will vary at various
frequencies. Mil. Std. 285 is the most commonly used test method
for developing the shielding effectiveness profile of an enclosure.
In order to accurately specify a shielded enclosure, there are two
basic questions that must be answered:
How much attenuation is needed?
That is, by how much do you need to reduce the signal strength as
it passes through the enclosure?
Which frequencies are problems?
In order to assure effective shielding performance, the problem
frequencies should be known. Just because an enclosure has EMI
gaskets doesn’t mean that it will shield the particular frequencies
that cause you problems. Shielding performance varies widely
from design to design and an enclosure manufacturer who has
experience in this area can help you “fine tune” your enclosure
choice to provide the most effective shielding at the most reason-
able cost. Typical enclosure performance profiles are based on
testing to Mil. Std. 285, which gives results for frequencies from
10K Hz to 10GHz. Other testing may be necessary for applica-
tions outside this frequency range.
2 Equipto Electronics Corp. Aurora, IL 800.204.7225 630.859.7840 Fax 630.897.5314
Shielded Enclosures from
System Equipto Electronics
Complex electronic systems often have an unwelcome side effect:
electro-magnetic and radio frequency interference (EMI/RFI).
More than just a nuisance, EMI/RFI can interfere with the opera-
tion of critical communication, computer and command and con-
trol systems.
As new equipment reaches higher and higher levels of perform-
ance and complexity, EMI/RFI can become a larger problem.
Packaging these types of electronic systems can be a difficult and
expensive design problem. Equipto Electronics has many years of
experience in the design and production of shielded enclosures
meeting requirements from commercial through military levels of
performance.
Equipto Electronics offers a wide variety of standard shielded
enclosures in many sizes. Since our shielded enclosures are based
on our proven Heavy Duty frame design, a wide variety of acces-
sories and options are available.
Shielded Enclosures-What’s important?
Shielding Performance EMI/RFI Cabinet Systems
Shielding performance is measured by attenuation. Attenuation is
the difference in signal strength between the inside and the out-
side of the enclosure and is measured in decibels (dB).
Attenuation characteristics of an enclosure will vary at various
frequencies. Mil. Std. 285 is the most commonly used test method
for developing the shielding effectiveness profile of an enclosure.
In order to accurately specify a shielded enclosure, there are two
basic questions that must be answered:
How much attenuation is needed?
That is, by how much do you need to reduce the signal strength as
it passes through the enclosure?
Which frequencies are problems?
In order to assure effective shielding performance, the problem
frequencies should be known. Just because an enclosure has EMI
gaskets doesn’t mean that it will shield the particular frequencies
that cause you problems. Shielding performance varies widely
from design to design and an enclosure manufacturer who has
experience in this area can help you “fine tune” your enclosure
choice to provide the most effective shielding at the most reason-
able cost. Typical enclosure performance profiles are based on
testing to Mil. Std. 285, which gives results for frequencies from
10K Hz to 10GHz. Other testing may be necessary for applica-
tions outside this frequency range.
2 Equipto Electronics Corp. Aurora, IL 800.204.7225 630.859.7840 Fax 630.897.5314
