Reduction Techniques of Undesired Electromagnetic Radiation Using DNG Materials

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It is very important for reducing undesired electromagnetic radiations using the DNG materials that how to realize appropriate electric and magnetic properties of the materials, and where the materials are set up. In this research, their fundamentals were investigated theoretically and experimentally. First, the basic properties of electromagnetic fields near the DNG slab were clarified by deriving an exact dyadic Green's function. For numerical simulations for the DNG materials, the FDTD method was improved for calculating the periodic structures effectively. Next, the lossy DNG materials could be synthesized chemically, we proposed a novel structure in which many conducting square plates are arranged periodically on an interface of a usual lossy material. Using this Electromagnetic Band-Gap structure, we made a new electromagnetic absorber. It has been found that this structure absorbs effectively and for wide frequency range. However it is necessary to reduce their sizes for practical uses. In this research, the representative unified the whole activity and studied theoretically the electric and magnetic properties and structures of the DNG materials, and proposed suitable structures for reducing the undesired electromagnetic radiation. A member of this research established the numerical simulation methods for DNG materials, and verified the effectiveness of the proposed techniques numerically and experimentally.