Micromachined polymer based components for highly integrated millimeterwave subsystems

La región de microondas en el espectro electromagnético tiene propiedades únicas que le permiten a las señales propagarse a través de la atmósfera bajo casi cualquier condición climática, ésta es la razón por la cual los sistemas de microondas han tenido un enorme impacto sobre la sociedad. En los últimos años se ha presentado una importante expansión en las comunicaciones móviles y en las redes de área local, emergiendo nuevas aplicaciones a frecuencias micro/milimétricas, tales como: la transmisión satelital a 35 GHz, las redes de área local de banda ancha a 60 GHz, comunicación entre vehículos a 63 GHz o en radares para evitar colisiones entre vehículos a 77 GHz. A medida que estas aplicaciones han emigrado a frecuencias más elevadas, las limitaciones de las tecnologías convencionales han sido visibles. Por lo cual en los últimos años se ha presentado un creciente interés en el desarrollo de nuevas técnicas de fabricación para la implementación de dispositivos de microondas; las cuales ofrezcan un mejor rendimiento del dispositivo a la vez que una reducción en sus dimensiones y en los costos de fabricación. El principal objetivo de este trabajo ha sido la implementación de dispositivos de filtrado en un amplio rango de frecuencias (banda X, U y V). Las topologías aquí presentadas son novedosas al introducir resonadores y líneas de alimentación suspendidas en aire, donde el uso de aire como dieléctrico permite obtener un factor de calidad mayor. Además el proceso de fabricación es relativamente simple y de bajo costo, ofreciendo estructuras compactas las cuales pueden ser altamente integradas. En la implementación de los dispositivos se utilizaron técnicas de maquinado convencional para los diseños en la banda X y técnicas de micromaquinado en SU-8 en los dispositivos de las bandas U y V. Las estructuras para la banda X fabricadas mediante maquinado convencional sirvieron como validación de las topologías a frecuencias más elevadas. Las estructuras diseñadas han demostrado la viabilidad de las topologías para un amplio rango de frecuencias, obteniendo resultados satisfactorios en cuanto a las prestaciones del dispositivo.The microwave region in the electromagnetic spectrum has properties that allow signals to propagate through the atmosphere under almost any weather condition, this is the reason why microwave systems have had an enormous impact on society. In recent years there has been a major expansion in mobile communications and local area networks, emerging new applications at micro/millimeterwave frequencies, such as: satellite transmission at 35 GHz, wideband local area networks at 60 GHz, communication among vehicles at 63 GHz or vehicular collision avoidance radar at 77 GHz. As these applications have migrated to higher frequencies, the limitations of conventional technologies have been visible. Therefore in recent years there has been a growing interest in the development of new manufacturing techniques for the implementation of microwave devices; which offer better device performance as well as a reduction in the size and manufacturing costs. The main objective of this work has been the implementation of filtering devices in a wide range of frequencies (X, U and V-band). The topologies presented are novel introducing resonators and air suspended feed lines, where the use of air as dielectric allows a higher quality factor. Besides manufacturing process is relatively simple and inexpensive, providing compact structures which can be highly integrated. In the implementation of the devices were used conventional machining techniques for X-band designs and micromachining techniques in SU-8 for U and V-band desings. The X-band structures manufactured by conventional machining served as validation of the topologies at higher frequencies. The designed structures have shown the feasibility of the topologies for a wide range of frequencies, with satisfactory results regarding the performance of the device

Optimal Sensor Placement in Environmental Research: Designing a Sensor Network under Uncertainty

Abstract. One of our main challenges in meteorology and environment research is that in many important remote areas, sensor coverage is sparse, leaving us with numerous blind spots. Placement and maintenance of sensors in these areas are expensive. It is therefore desirable to find out how, within a given budget, we can design a sensor network are important activities was developing reasonable techniques for sensor that would provide us with the largest amount of useful information while minimizing the size of the “blind spot ” areas which is not covered by the sensors. This problem is very difficult even to formulate in precise terms because of the huge uncertainty. There are two important aspects of this problem: (1) how to best distribute the sensors over the large area, and (2) what is the best location of each sensor in the corresponding zone. There is some researcj on the first aspect of the problem. In this paper, we illustrate the second aspect of the problem, on the example of optimal selection of locations for the Eddy towers, an important micrometeorological instrument

Dispositivos coaxiales micromecanizados para banda milimétrica

This paper presents compact micromachined coaxial devices for millimeter wave applications at U and V bands. The coaxial center conductor is suspende d in air by short circuits to the outer conductor. The designs include a suspended transmission line, two narrowband filters and a diplexer.Peer ReviewedPostprint (published version

Review on Microwave and Millimeter Filters Using MEMS Technology

Abstrac

Consequences of gas flux model choice on the interpretation of metabolic balance across 15 lakes

Ecosystem metabolism and the contribution of carbon dioxide from lakes to the atmosphere can be estimated from free-water gas measurements through the use of mass balance models, which rely on a gas transfer coefficient (k) to model gas exchange with the atmosphere. Theoretical and empirically based models of k range in complexity from wind-driven power functions to complex surface renewal models; however, model choice is rarely considered in most studies of lake metabolism. This study used high-frequency data from 15 lakes provided by the Global Lake Ecological Observatory Network (GLEON) to study how model choice of k influenced estimates of lake metabolism and gas exchange with the atmosphere. We tested 6 models of k on lakes chosen to span broad gradients in surface area and trophic states; a metabolism model was then fit to all 6 outputs of k data. We found that hourly values for k were substantially different between models and, at an annual scale, resulted in significantly different estimates of lake metabolism and gas exchange with the atmosphere

Furthering Our Understanding And Assessing The Effectiveness Of Scaling Patterns And Controls Of Land-Atmosphere Carbon Exchange In A Shrubland Of The Chihuahuan Desert With Novel Cyberinfrastructure

Over the last century, arid and semiarid regions have undergone intense desertification and in many regions, vegetation has shifted from grassland to shrubland dominated ecosystems. This land cover change has important implications for how desert ecosystems function - especially with regards to land-atmosphere exchange of carbon, water, and energy. Although the extent of desertified landscapes is expected to expand over the next 30 to 40 years, there is a relatively poor understanding of how this state transition will impact ecosystem function and feedbacks to other components of the earth system. Key to addressing this challenge is an improved understanding of ecosystem dynamics and land-atmosphere interactions at the landscape scale, and a capacity to extrapolate ecosystem dynamics to regional scales using remote sensing. This study addresses both the scientific and technical aspects of the above challenges to further our understanding of biophysical controls of ecosystem fluxes of carbon of shrublands representative of the Northern Chihuahua Desert, and also assess the effectiveness of scaling ecosystem fluxes using spectral and greenness indices derived from two spectral platforms using established, repurposed, and novel Cyber infrastructure. The study was completed through interdisciplinary collaborations within the University of Texas at El Paso\u27s (UTEP) Cyber-ShARE Center that includes faculty and students affiliated with the environmental, computational, geological, social, and computer sciences. Several publications and conference proceedings have arisen from these collaborations. This project also intends to facilitate long term and synThesis studies through data submission to the network, and to provide a data stream for the data information system developed by fellow staff and graduate students of the Systems Ecology Laboratory at UTEP

Furthering our understanding and scaling patterns and controls of land-atmosphere carbon, water and energy exchange in a Chihuahuan Desert shrubland with novel Cyberinfrastructure

Over the last century, arid and semiarid regions have undergone intense desertification and in many regions, vegetation has shifted from grassland to shrubland dominated ecosystems. This land cover change has important implications for how desert ecosystems function – especially with regards to land-atmosphere exchange of carbon, water, and energy. Although the extent of desertified landscapes is expected to expand over the next 30 to 40 years, there is a relatively poor understanding of how this state transition will impact ecosystem function and feedbacks to other components of the earth system. Key to addressing this challenge is an improved understanding of ecosystem dynamics and land-atmosphere interactions at the landscape scale, and a capacity to extrapolate ecosystem dynamics to regional scales using remote sensing. This study addresses both the scientific and technical aspects of the above challenges to further our understanding of biophysical controls of ecosystem fluxes of carbon of shrublands representative of the Northern Chihuahua Desert, and also assess the effectiveness of scaling ecosystem fluxes using spectral and greenness indices derived from two spectral platforms using established, repurposed, and novel Cyber infrastructure. The study was completed through interdisciplinary collaborations within the University of Texas at El Paso\u27s (UTEP) Cyber-ShARE Center that includes faculty and students affiliated with the environmental, computational, geological, social, and computer sciences. Several publications and conference proceedings have arisen from these collaborations. This project also intends to facilitate long term and synthesis studies through data submission to the network, and to provide a data stream for the data information system developed by fellow staff and graduate students of the Systems Ecology Laboratory at UTEP