EMI-RFI Shielding For Enclosure Windows—The Resources Engineers Need

At MAJR Products, our team of design engineers, technicians, and product support professionals understands that, and we’re here to help you streamline your design process.

So in this post, we’re going to provide EMI and RFI engineers and designers with the information and resources you need to solve the most complex enclosure window design challenges.

Here’s what you’ll learn:

  • What Makes EMI Shielding Window Design For SCIFs And Secure Enclosures So Challenging? 
  • What Are The Primary Issues To Be Aware Of In Secure Enclosure Window Design?
  • What Types Of Engineered Products Do RFI And EMI Engineers Need For Secure SCIF and Enclosure Window Design?
  • Where Can You Go For More Information?

If that sounds good, let’s get started with the basics.

What Makes EMI Shielding Window Design For SCIFs And Secure Enclosures So Challenging? 

majr products emi shielding blog situation room

The Situation Room-Courtesy of HowStuffWorks.com

Wherever there’s a window aperture in a hardened enclosure, whether it’s in an opening as small as a handheld device or as large as a man door, there is the potential for unwanted EMI.

Shielded windows are designed to solve this fundamental problem. These specially designed windows allow for the physical separation between the interior and exterior of a shielded enclosure while fulfilling two additional requirements: 

  • Transparency for Viewing 
  • EMI and RFI Attenuation  

Windows may be required in secure boxes, enclosures and SCIFs for several reasons.

majr products emi shielding blog military

In medical devices, for example, units with displays often use EMI resistant windows and films to allow healthcare professionals to see inside and read data collected by the device. In this case, visual transparency and EMI attenuation are both critical to maintain levels of optimal equipment performance and accuracy. 

Shielded windows can be quite small, as in the referenced use case, but they are often crucial to the users of the device.  

majr products emi shielding blog control panel

On the larger end of the spectrum, shielded windows can be the size of large panels in sensitive and secure DoD applications, such as manned, military-hardened enclosures, vehicles, SCIFs and secure buildings and workspaces. In this case, where human safety, comfort, exterior light, and external visibility are essential, EMI-shielded windows could provide protection from unintentional, or intentional, electromagnetic interference and signals while allowing exterior light and visibility in the secure space. 

EMI protected windows can protect against unwanted signals entering the enclosure as well as signal leakage emanating from the inside.

So What Are The Primary Issues To Be Aware Of In Secure Enclosure Window Design?

Regardless of the size and application of the enclosure window, the goal is to prevent unwanted levels of RFI and EMI propagation into and out of the enclosure.

Given that fundamental objective, there are several ways to approach window design for SCIFs and other secure enclosures. These approaches depend on the application, the level of attenuation required, and the materials available to achieve it.  

Design considerations include: 

  • target signal frequency ranges, 
  • desired levels of EMI/RFI attenuation, 
  • importance of the optical capabilities of the window, additional military or commercial specs, etc.

We should also mention that the design approaches and the underlying material selections are not mutually exclusive. There can be an either-or, some of both, or an all-the-above approach, depending on your enclosure.

So let’s put window design and EMI resistive materials and designs into context.

What Types Of Engineered Products Do RFI And EMI Engineers Need For Secure SCIF Window Design?

Preventing EMI and RFI in secure enclosure window design essentially boils down to two fundamental design techniques:

  • Coating the window with a conductive coating material or film. 
  • Incorporating an embedded mesh in the window material

Let’s consider the first option, using silver conductive film.

majr products emi shielding blog silver conductive film

Silver conductive film is an electrically conductive, silver alloy coated, optically clear, low resistance polyester EMI/RFI shielding film. The combination of high visible light transmission, near-neutral color, and low resistance provides for an optimal EMI/RFI shielded window for electronic displays, touch screens, and membrane switch panels (touch screens). 

Conductive coatings also offer a quick and easy-to-apply solution for shielding plastic enclosures. These specialty coatings can simultaneously and cost-effectively provide superior EMI shielding and suppression of electrostatic discharge (ESD).

Conductive films are also an excellent solution for applications that require moderate shielding effectiveness and high-quality optical performance. These coatings are optimal for use in EMI/RFI shielding designs in industrial and DoD applications, medical and commercial device display applications, touch screens, solar photovoltaic material, and in conductive transparent electrodes.

What about shielded mesh windows? 

Be sure to check out our previous post for more details.

In a nutshell EMI shielded windows from MAJR Products are manufactured in a proprietary process where fine mesh optical wire is embedded between sheets made of polycarbonates, acrylic, and glass. This process provides superior optical qualities, while still meeting demanding shielding requirements. Operationally, as the mesh captures electromagnetic radio frequencies, it passes these unwanted signals to the perimeter busbar and then to ground. 

majr products emi shielding blog emi shielded windows

This may sound simple and straightforward. But in our decades of working with EMI and RFI engineers, we’ve learned that there are just about as many design considerations that need to be evaluated as there are real-world applications.

So which design approach and material selection is right for your project? Do you have questions about product specifications, available materials, lead times, and costs?

It also might not be an either-or decision on design approach or materials selection.

So where do you go from here?

The MAJR Products Team is Here With The Information You Need

MAJR is an internationally recognized leader in designing and fulfilling the highest quality shielded window products. 

We also provide many additional EMI and RFI shielding solutions and products for commercial and government applications. 

At MAJR Products, we understand the need for competitive pricing and lead times. We also offer product and application design guides and assistance from our shielding experts. Get in touch with us online, or simply click on the “Request a Quote” button on the top right of any of our web pages. You can also always call us at (877) 625-6033.