چكيده به لاتين
Metamaterials are materials that consist of structures with dimensions below the wavelength and have interesting properties that are not seen in natural materials. These materials have been used in recent years for various applications, both in industry and in the military. Among the applications of metamaterials that have been used in recent years, we can mention such things as refractive index close to zero, hiding objects, changing the direction of the insurances and adjusting the power of the insurances. Compared to metamaterial structures that are voluminous, there are also structures known as supersurfaces, and the thickness of these structures is reduced as much as possible. The main reason for turning to superficials compared to metamaterials was to overcome the complexity of construction, high losses, bulky profiles and higher costs. Electromagnetic wave control has long been of interest to researchers due to its many applications. Among its applications, we can mention the conduction of electromagnetic waves in arbitrary directions. Using adjustable materials, both in the terahertz band and in the GHz band, various applications such as changing the focus point of the lens, etc. can be mentioned. One of the cases that has been considered recently is capturing different phases using adjustable structures that can be done instantly by changing the bias of the system, capturing multiple beams at different angles or reducing the radar cross section. The advantage of using adjustable materials in this type of antennas is that it is no longer necessary to give different phases to the structure by feeding the antenna, but by changing the bias of this type of material, different phases can be obtained. Also, with the help of metamaterials, in the last decade, they have been able to design metamaterial absorbers that are used in medical fields, optical integrated circuits and other technologies. Recently, the design of absorbers that can maintain the stability of their absorption rate in the appropriate frequency range under different radiation angles has been highly regarded. In this dissertation, we have designed an absorber that has good angular stability in the terahertz band.
