EMI Benefits of
ZARGES Aluminum Cases
For delicate or regulated equipment generally, see the guide to protecting sensitive equipment in transport.
For most applications, EMI shielding requires a Faraday cage around the equipment requiring protection. Any gap in the cage will allow some leakage, and if the case contents are susceptible to that frequency range — or if sensitive data can be compromised by the emission of those frequencies — the EMI shielding is inadequate.
Aluminum offers many advantages over typical composite case construction. It can weather extreme temperatures, resist impact without cracking, and will not rust or corrode over time. ZARGES cases are free of ferromagnetism and are an excellent conductor of electricity and heat. The Mitraset line of aluminum rackmount cases for electronic installations is inherently shielded against EMI.
Aluminum cases can be fabricated with welded or formed seams to eliminate most radiation leakage with little additional cost in manufacturing. Plastic and composite materials require a conductive supplement to the nonconductive base material, which significantly increases material and labor costs — and these supplemental materials are difficult to apply and easily damaged in rough handling or temperature extremes.
EMI Shielding Features
of ZARGES Cases
The Mitraset and K475 cases passed the shielding requirements of 60dB from 150kHz to 18GHz. The tests were performed at Chomerics, Inc. of Woburn, MA. The assessment determined that the Mitraset complies with the requirements set forth in IEEE STD 299.
Mitraset housings have also been measured to MIL-STD-285, the US military standard that IEEE STD 299 replaced. For tighter requirements ZARGES can add an RF honeycomb filter in the lid, an RFI gasket on the rack frame, and a conductive chromate coating, free of hexavalent chromium, that keeps the shielding consistent and is fully RoHS‑compliant.
As a custom option, the Mitraset and K475 cases can be fitted with an EMI shielding gasket made from Chomerics CHO-SEAL 1285 — silver-plated aluminum in silicone — providing additional shielding between 90–110 dB.
Independent test data, Chomerics, Inc. — SE (E-Field and Plane Wave) vs. the 60dB compliance limit, 150kHz–18GHz.
What Is EMI/RFI?
Electromagnetic interference (EMI), or radio frequency interference (RFI) when in the radio frequency range, is a disturbance that affects an electrical circuit due to electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit — effects can range from a simple degradation of data to a total loss of data. The source may be any object, artificial or natural, that carries rapidly changing electrical currents, such as an electrical circuit, the Sun, or the Northern Lights.
What Is a Faraday Cage?
A Faraday cage is an enclosure formed from conductive material, or a mesh of such material, that blocks external electric fields. Electricity is channeled along the surface, maintaining a constant potential and preventing penetration into the interior. The concept was demonstrated in 1836 by English scientist Michael Faraday, for whom the device is named.
The principle of operation relies on the redistribution of charges within the conducting material. When exposed to an external static field, these charges arrange themselves in a way that cancels the field inside the enclosure — shielding sensitive electronic equipment from lightning strikes and electrostatic discharge.
Faraday cages also attenuate electromagnetic radiation when the conductor is sufficiently thick and any openings are much smaller than the wavelength of the radiation. Grounding the conductive layers dissipates induced currents from external and internal sources, further enhancing protection — greatly reducing electromagnetic interference and heavily blocking the transmission or reception of radio waves within the cage.
Faraday cage explanation adapted from Wikipedia, CC-BY-SA.
FAQ
SUPERIOR
Protection.
Lightweight & Strong
- 50% lighter than plastic cases*
- 70% lighter than roadie cases*
- Rugged, fully-welded profile frame
- Will not warp or crack
Durability & Resistance
- 2-7x greater tensile strength than plastic cases*
- Tested from −65° to +176°F; UV, water, weather, and corrosion resistance
- Ergonomic spring-loaded handles
- Over 50 standard sizes available
Optimized Space & Security
- 15%-20% greater interior volume than plastic cases in a smaller footprint
- IP54 sealed against dust and splashing water as standard
- Locking options available for theft protection
Specialized Features
- IGBC (Interagency Grizzly Bear Committee) models available
- Cases constructed of extra strong 5005 alloy aluminum sheeting
*Comparisons based on industry-standard plastic and roadie cases of equivalent size.
