Isolation Improvement with Electromagnetic Band Gap Surfaces

An electromagnetic band gap (EBG) material is a periodic surface specifically designed to have certain electromagnetic properties at specific frequencies. The term “metamaterial” is sometimes used to describe such engineered surfaces. Metamaterials (“meta” means “beyond” in Greek) are man-made materials not found in nature and designed by placing tiny resonant structures at regularly spaced distances to create the appearance of a different bulk propagation medium [1]. As long as the inserted structures, called cells, are very small compared to the propagating wavelength, they can create a macroscopic effect on the electromagnetic wave as it passes through the new medium. Figure 1 depicts the engineered material’s macro/micro “atomic” geometry approximation and the corresponding periodic unit cell. Desired electromagnetic properties can include specific values of permittivity, permeability, reflected phase, and index of refraction. If such media could be realized, then human beings could control the propagation of electromagnetic waves in previously unfeasible ways [1].* EBGs are a class of metamaterials whose purpose is to highly impede electromagnetic propagation along the device’s surface within the frequency band of operation known as a “band gap” (hence the name “electromagnetic band gap” material) [2]. In this sense, it is an artificially high-impedance surface and blocks current from flowing at microwave frequencies. In contrast, normal metals A new type of engineered surface called an electromagnetic band gap blocks current from flowing at microwave frequencies. One application of this metamaterial is to employ the surface amid electronic devices to improve the electromagnetic isolation between them. The different geometry features of the device’s individual unit cells create extra inductances and capacitances for electromagnetic waves. When the unit cell is properly tuned, the aggregate surface will block incoming signals just as a band-stop filter will. This additional isolation allows radio-frequency receivers to operate in closer proximity to transmitters than a normal metal surface would permit. »