Electromagnetic interference is radiation emitted from an external source. Electromagnetic interference can adversely affect electrical circuits, cell phones, televisions, satellite communications, GPS, electrical grids, etc. With these electronics so prevalent in today’s world, research into different kinds of shielding to protect against harsh electromagnetic environments is on the rise.
NanoMetaShielding materials can used in various applications such as laptops, GPS, wireless communications, and microwave/radar absorbent materials.
Conventional electromagnetic interference shielding is usually made of highly conductive materials. The shielding’s performance is characterized by the shielding effectiveness, which is affected by reflection, absorption, and other properties. In general, there are two practical solutions for EMI shielding. The first is to protect certain components from external EMI by reflection and/or absorption. The second is to reduce reflection on metal surfaces and dissipate the electromagnetic energy in the form of heat. Spectrum Magnetics LLC focuses on the second type of shielding, also known as microwave absorbent material or radar absorbent materials.
Radar absorbent materials can significantly reduce the radar cross-section of an object at specific frequencies. One of most commonly known radar absorbent materials is iron ball paint, paint that contains tiny spheres coated with carbonyl iron or ferrite. Carbon black or fibers are another important example.
In general, radar absorbent materials can be categorized into four basic types of materials:
1. Dielectric absorbent
2. Magnetic absorbent
3. Resonant absorbent
Complex dielectric permittivity (ε = ε’ – iε”) and permeability (μ = μ’ – iμ”) are two important parameters describing the properties of these materials. The imaginary parts of permittivity and permeability are associated with the energy losses. Therefore, good radar absorbent materials usually require a large dielectric loss tangent (ε”/ε’) and magnetic loss tangent (μ”/μ’). Additionally, radar absorbent materials are also made of materials with matched impedance or gradually matched impedance similar to that of air in order to reduce reflection.
Spectrum Magnetics LLC has developed radar absorbent materials based on nanocomposites for various frequency bands from 10 MHz to 10 GHz or higher. The impedance of our radar absorbent materials can be tailored to match that of air.