Method of measuring the amounts of electromagnetic radiation absorbed and controlled by metamaterials in anechoic chamber

This study has proposed a method of measuring the characteristics of electromagnetic (EM)-wave absorption and diffraction using MM absorbers (MAs). Metamaterials (MMs) can absorb or affect EM waves towards desired directions. There are a number of ongoing studies on the development of MAs for EM waves. However, as of yet no method of quantitatively evaluating the EM waves absorbed by MM has been clearly defined. It has been explained that the EM characteristics caused by MMs can be explained using Poyntings vector theorem. However, it is necessary to develop a practical alternative to the use of this theorem, because the theoretical evaluations have limitations due to the ideal properties of an antenna for measurement of EM waves and the size of MMs. Thus, this study has suggested that factors to be considered in measuring the characteristics of EM waves absorbed by MMs include distance between MM and antenna, performance characteristics of antenna, conditions of test field, measuring instrument, and measuring system. With a measurement system established, the MMs EM characteristics, which are represented by the amounts of EM waves absorbed and controlled by MMs, can be measured by generating EM waves from the antenna and comparing the differences between when there is a MM absorber and when there is no MM absorber at a location which is a certain distance (far-field) away from the source of the EM waves. This study has shown the amounts of EM waves absorbed by and controlled by MMs by using antennas with 2.4 and 4 GHz bandwidths.