Complete with embedded wireless capabilities, high-speed circuits and high definition graphical interfaces, modern military hardware is becoming increasingly complex. Growing technological complexities are in turn making them vulnerable to radio frequency interference (RFI) threats – a kind of electronic disturbance that can be produced by a range of electronic or electromechanical devices including personal computer and computer games, medical instruments, industrial controls and many more. The radiated energy or electronic noise often affects the performance of sensitive defense equipment such as computer windows, displays on global positioning systems and military vehicles. They start responding to these disturbances randomly and erratically, subsequently leading to dangerous outcomes. RFI shielding offers a solution to this problem. It is a protective technology that helps to manage this interference and helps ensure the reliability and functionality of the components, interconnects and subsystems within these equipment.

Controlling RFI

Electronic or electrical devices directly release RFI into the environment. There can also be the conducted RFI which comes out of various electronic gadgets and penetrates the power line chords in the vicinity. This in turn interferes with the performance of other devices on the same network. This penetration can be controlled by placing a shield right at the enclosure of the equipment. A power line filter is placed to suppress the radiation leaving the unit. This helps reduce RFI to moderate levels. Different types of shielding materials are used to provide military compliant shielding performance. These materials must be lightweight, yet sturdy, capable of withstanding extreme environmental conditions, and optically transparent.

Different RFI Materials in Use

RFI shielding solutions come in many shapes and sizes, and range from simple metal boxes to conductive foams and metal meshes. When it comes to protecting displays and touch screens from electromagnetic radiation, transparent conductive films are becoming the first choice of the military around the globe. Indium Tin Oxide (ITO) is one of the substances that is widely used to manufacture such conductive films.

Depending on the level of the radio frequency, these materials can provide up to 35dB shielding effectiveness. There are many other optically transparent materials, such as conductive polymer, carbon nanotube and grapheme. However, they are not used in defense as they provide less than 20dB shielding results which is far below the military shielding requirements.

Some advanced composite materials are also growing in popularity due to their lightweight, stability and resistance to chemical reaction-induced temperature changes. These high-performing materials are being increasingly used to meet aerospace shielding requirements.

With a shielding effectiveness of more than 60dB, metal mesh is widely employed to protect key military equipment such as laptops and handheld computers, battlefield tactic systems and other types of communication systems from RFI. There are many benefits of using wire mesh shielding. Being extremely sturdy and resistant to fire and corrosion, they are ideal for battlefield conditions. Different types of pliable metals including copper, stainless steel and aluminum can be used to build this extremely thin mesh. In addition, they can be easily manipulated to address different military application needs.

Proper shielding of devices enables military personnel to avoid risks of sending unintended signals which may alert unauthorized persons in the vicinity. No wonder, the military and the governments of major industrialized nations including the United States, Canada, Germany, Sweden, and Switzerland, have embraced comprehensive RFI shielding regulations to reduce the vulnerability of military hardware systems to potentially dangerous electronic disturbances. With aerospace and defense equipment becoming increasingly complex, shielding solutions are expected to become increasingly more stringent in order to be able to withstand more sophisticated RFI attacks.