Publication: Estructura EBG para disminución de la radiación trasera en parches
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2012-03
Defense date
2012-03-13
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Abstract
Este Proyecto Fin de Carrera nace por las necesidades de la sociedad actual, en la que cada vez es más habitual la aparición de dispositivos cuya cercanía con el cuerpo humano es más significativa. Esta proximidad provoca que la disminución de la radiación emitida hacia la persona que lo porta sea de vital importancia, y es por esto, por lo que en este estudio se presentará una solución para poder mitigar en la medida de lo posible la radiación trasera. Se estudia el comportamiento de una estructura periódica de forma aislada e integrada con un parche para evaluar el efecto que produce sobre este último. La banda de frecuencia elegida es la ISM (2.4 a 2.5 GHz) en la que se encuentran las comunicaciones WLAN y WPAN. El diseño se realizará en fibra de vidrio y se ampliará el estudio a las antenas textiles. Este tipo de antenas tiene como característica que están realizadas con materiales textiles y, de esta forma, pueden ir adheridas a la ropa formando parte de la vestimenta Se realiza el modelado de la estructura EBG en dos versiones diferentes, mediante vías y paredes metálicas, y en los dos substratos especificados. Se optimiza ésta para que trabaje en la frecuencia adecuada mediante diferentes estrategias. En una de ellas se hallan los diagramas de dispersión, para lo que se ha de suponer una estructura infinita, mientras que el otro método realiza simulaciones de onda completa, simulando la transmisión en dos configuraciones, con línea microstrip suspendida y sin línea. Por otro lado, se diseña el parche a la misma frecuencia y en los dos substratos elegidos, y una vez optimizada, se procede a combinar ambas estructuras. Tras la integración de la EBG se estudia de qué forma modifica el comportamiento de la antena, para ello se analiza el parámetro de reflexión, la ganancia, y mediante sondas de campo se cuantifica si se reduce la propagación de ondas de superficie. Gracias a las simulaciones realizadas se ha comprobado como la estructura periódica ayuda a reducir la radiación trasera y a aumentar la ganancia respecto del caso en el que únicamente se disponía del parche. Finalmente, para confirmar el funcionamiento real del diseño, se ha construido un prototipo de antena sobre fibra de vidrio que incorpora una de las configuraciones estudiadas. Comparando los resultados experimentales y los simulados se ha comprobado como el funcionamiento es bastante similar en adaptación. ____________________________________________________________________________________________________________________________________
Nowadays it is usual to find devices which are really close to our body. This proximity makes that the radiation delivered to people who carry them must be take care into account and it should be minimize. The purpose of this work is to find a way to reduce back radiation. Lately, new researches have been risen due to steps forward in technology, for example, textile antennas. This kind of antennas is characterized by its materials which are textile and allow them to integrate into clothes. This work analyzes a structure to reduce back radiation. Because of the importance of textile antennas there is a study about them describing possible applications and common and commercialized materials. As it was said before, devices close to our body are more common, therefore, this work not just deals with a solution for textile antennas, but it is also presented a solution for other materials, in this case, FR. The design consists of a patch and an electromagnectic bandgap structure (EBG) that reduces back radiation. ISM is the frequency band used (2.4 – 2.5 GHz). Two types of EBG’s are studied, one with shorting pins and the other one with metallic walls. Besides, designs are simulated with different permittivities (FR and textile). EBG’s are modified with different procedures to obtain the best response in the designated frequency. On the other hand, patch is designed to work at the same frequency and permittivities. Patch and EBG are integrated together to check if back radiation is reduced. Finally, a prototype is constructed and measured to verify the real behaviour.
Nowadays it is usual to find devices which are really close to our body. This proximity makes that the radiation delivered to people who carry them must be take care into account and it should be minimize. The purpose of this work is to find a way to reduce back radiation. Lately, new researches have been risen due to steps forward in technology, for example, textile antennas. This kind of antennas is characterized by its materials which are textile and allow them to integrate into clothes. This work analyzes a structure to reduce back radiation. Because of the importance of textile antennas there is a study about them describing possible applications and common and commercialized materials. As it was said before, devices close to our body are more common, therefore, this work not just deals with a solution for textile antennas, but it is also presented a solution for other materials, in this case, FR. The design consists of a patch and an electromagnectic bandgap structure (EBG) that reduces back radiation. ISM is the frequency band used (2.4 – 2.5 GHz). Two types of EBG’s are studied, one with shorting pins and the other one with metallic walls. Besides, designs are simulated with different permittivities (FR and textile). EBG’s are modified with different procedures to obtain the best response in the designated frequency. On the other hand, patch is designed to work at the same frequency and permittivities. Patch and EBG are integrated together to check if back radiation is reduced. Finally, a prototype is constructed and measured to verify the real behaviour.
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Keywords
Antenas, Radiación, Radioprotección