Navy

Transparent electromagnetic shielding

Hybrid material can be applied to any surface that requires maintained visibility and electrical isolation

Materials

The Navy recently developed a hybrid transparent electromagnetic shield. The technology is available to businesses through a patent license agreement. Companies interested can contact TechLink for more details on the licensing process and cost.

Windshields on airplanes may be an application for transparent electromagnetic shielding. (Micaiah Anthony/USAF)

Electromagnetic (EM) shielding is commonly used to protect sensitive electronics from radiation interference as it effectively reduces the transmission of an electromagnetic field by blocking it with a conductor or magnetic material. The amount of shielding needed depends strongly on the type of material used, its size, shape, and orientation with respect to the incoming radiation.

Transparent EM shielding is necessary for any application in which humans need to maintain visibility while being electrically isolated, such as in an airplane cockpit. This need may be extended to auto glass given the ever-increasing amount of radio transmissions in the connected world and the increase in onboard electronics in modern vehicles.

Several materials have been used in transparent EM shields including metallic meshes, metal powders in a glass matrix, and conducting oxides. However, these materials each have significant drawbacks. Metallic meshes are often bulky and expensive. Metal powders are typically costly. For example, gold is desirable in shielding due it to its chemical inertness, yet gold is prohibitively expensive for most applications. Other particles can oxidize and degrade in performance. Conductive oxides, such as indium-tin-oxide (ITO) and fluorine-doped tin oxide (FTO), are brittle and moderately resistive, making them poor shielding materials.

The Navy recently developed a hybrid transparent electromagnetic shield that exhibits effective electromagnetic shielding, yet is optically transparent. The material includes a metal nanomesh structure with an overlaid graphene sheet. The nanomesh/graphene sheet is relatively lightweight and inexpensive to manufacture.

The design is expected to provide optical transparency greater than 85 percent, low sheet resistance (less than 5 ohms/square) and high carrier mobility (greater than 1,000 centimeters squared per Volt-second for graphene). The conformable, transparent shielding is capable of blocking electromagnetic radiation from the Megahertz to Gigahertz frequency range.

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