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Optimización de superficies metamateriales para su aplicación en el diseño de estructuras sintonizables reductoras de la sección recta radar
| Content Provider | Semantic Scholar |
|---|---|
| Author | Gomez, Ismael |
| Copyright Year | 2015 |
| Abstract | III ABSTRACT A chessboard structure is a metamaterial surface composed by two types of cells which reduce the radar cross-section, by creating a destructive interference in between reflected fields in both cells. The phase difference that must exist between the two types of cells is 180o. Using PEC cells ("Perfect Electric Conductor"), which introduce a phase shift of 180° to the reflected wave, and AMC cells ("Artificial Magnetic Conductor”) which introduce a phase shift of 0o in one frequency, called resonant frequency, the destructive interference can be generated. If the PEC cells is changed by another AMC cell, a structure that works in two frequencies, one for each resonance frequency of the AMC, since the AMC away from the resonance frequency having behavior of a PEC is obtained. A broadband chessboard structure can be designed by keeping the 180o difference between phase reflection curves in a large bandwidth. In this Final Degree Project an improved chessboard structure is proposed. The feasibility of designing a tunable structure by varying the value of the permittivity of the substrate to increase the bandwidth in which the chessboard reduces the radar cross section has been studied. Also, tuning technologies that could be implemented, such as liquid crystals or BST, have been studied. The project begins with a study of different types of AMC to check if there is a direct relationship between how resonant structures are and how the change of the permittivity value of the substrate to these cells affects, to find which one has a greater variation. After selecting the AMC structure, a study to find two types of cells which present a broadband destructive interference has been done. Once these two AMC have been obtained, the behavior of a chessboard structure formed by these two types of unit cells, before a change in the value of the permittivity of the substrate has been studied. Once it has been shown that by changing the value of the permittivity the frequency range in which the structure reduces the radar cross section varies, a study to manufacture, a chessboard for two permittivity values has been done, using two types of materials with different permittivity value. It has been probed that there is a frequency shift by changing the permittivity value. This design is a preliminary step before implementing the structure in liquid crystals technology. The final liquid crystal design has been the permittivity variation given by the commercial liquid crystal GT3-23001. Finally, after checking that the same structure with two different substrates operates in different frequency ranges, it has been adapted to liquid crystals technologies. It has been necessary to feed the AMC structures to allow applying a voltage and polarizing the crystals to change the value of permittivity. Therefore, the sizes of the AMC need to be readapted and power lanes had to be included. The memory finishes with the conclusions derived from the Final Degree Project together with the future lines. Ismael Hernández Gómez Universidad Pública de Navarra |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://academica-e.unavarra.es/bitstream/handle/2454/18064/629331.pdf;jsessionid=1209414C25561512FE3866168E4A9423?sequence=1 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
