Flexible Antennas Design and Test for Human Body Applications Scenarios Electrical and ...

114 Pages·2015·2.9 MB·English

Flexible Antennas Design and Test for Human Body
Applications Scenarios
Jo˜ao Vicente Faria
Thesis to obtain the Master of Science Degree in
Electrical and Computer Engineering
Supervisor: Professor Ant´onio Manuel Restani Gra¸ca Alves Moreira
Examination Committee
Chairperson: Professor Jos´e Eduardo Charters Ribeiro da Cunha Sanguino
Supervisor: Professor Ant´onio Manuel Restani Gra¸ca Alves Moreira
Members of the Committee: Professor Paulo S´ergio de Brito Andr´e
May, 2015
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Dedicated to my family and friends
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Acknowledgments
Firstly, i would like to express my sincerest thanks to my supervisor, Prof. Ant´onio Moreira, for all
the constant support and incessant guidance along the development of this thesis. His knowledge and
experience sharing, as well as his kindness and friendliness were crucial to solve my problems and to
complete this work.
I would like to thank to Mr. Carlos Brito and Mr. Farinha, the first one for the assistance in
prototypingtheantennas,andthesecondoneforcreatingthenecessarysetuptotesttheantennasunder
bending scenarios. I also thank to Engineer Ant´onio Almeida for his availability and time spent with the
measurements.
I should like to say a special thank you to Mr. D´elio Vicente and Mr. Paulo Teixeira from EDP
FabLAB for giving me the possibility to use their space to produce the antennas patterns. I would also
like to thank to Engineer Jo˜ao Costa for helping me to solve some design problems with CST Microwave
StudioTM, specially in the bending setup simulation.
My warmest thanks to all of my friends and colleagues who followed, motivated, and encouraged me
along these memorable academic years.
I cannot end my acknowledgements without expressing my heartfelt gratitude to my parents and
brotherfortheirunlimitedsupportandforbelievingmeallthetime. Iowetothemeverything,including
my personal and academic growth.
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Resumo
Neste trabalho apresenta-se uma antena flex´ıvel para operar na banda Ultra-Wideband (UWB), uti-
lizada para aplicac¸˜oes na proximidade do corpo humano. A estrutura principal da antena consiste num
elemento met´alico em forma de folha e num plano de terra sim´etrico, ambos impressos na mesma face
do substrato. Esta antena foi projectada e, posteriormente, fabricada com base em diferentes materiais
(papel e Kapton(cid:114)) e utilizando processos de fabrico distintos. Os resultados das medi¸c˜oes e das sim-
ula¸c˜oes para o m´odulo do coeficiente de reflex˜ao, diagramas de radiac¸˜ao e eficiˆencias totais e de radia¸c˜ao
mostram que a antena tem um bom desempenho em espa¸co livre.
De forma a ajustar facilmente a antena `a superf´ıcie do corpo humano, esta foi concebida para ser
flex´ıvel, compacta e robusta do ponto de vista mecˆanico. Como tal, foram analisados os efeitos da
dobragem e do amarrotamento no desempenho da antena. Os resultados das simula¸c˜oes e das medi¸c˜oes
mostraramque,aocontr´ariodoqueaconteceparadeforma¸c˜oesmaisacentuadas,emcasosdedeformac¸˜oes
mais suaves, a antena opera de forma satisfat´oria.
Finalmente,foiestudadoodesempenhoelectromagn´eticodaantenanaproximidadedobra¸cohumano.
Para simular a antena nestas condi¸c˜oes, foram apresentados quatro modelos do brac¸o humano com difer-
entes propriedades geom´etricas e diel´ectricas. O m´odulo do coeficiente de reflex˜ao, eficiˆencia total, e
diagramas de radiac¸˜ao foram analisados para diferentes distˆancias entre a antena e o corpo humano.
Foram tamb´em realizadas medi¸c˜oes na presenc¸a de um modelo humano real, com a antena colocada a 3
e 6 mm do bra¸co.
Palavras-chave:
Antena flex´ıvel, Ultra-Wideband (UWB), aplica¸c˜oes na proximidade do
corpo humano, m´odulo do coeficiente de reflex˜ao, dobragem, amarrotamentento.
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Abstract
This work presents a flexible Coplanar Waveguide (CPW)-fed acacUWB monopole antenna used for
applicationsintheproximityofthehumanbody. Theantennastructureconsistofaleaf-shaperadiating
patch and a symmetric ground plane both printed on the same side of the dielectric substrate. The
proposed antenna has been designed, and subsequently fabricated on two different substrate materials
(standard commercial paper and Kapton(cid:114)) using two distinct fabrication processes. The simulated and
measured results for the return loss (|S |), radiation patterns and total and radiation efficiencies are in
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good agreement, showing that the antenna has a very good performance in free-space.
Toeasilyconformtothebodysurface,thesuggestedUWBantennawasdesignedtomeettherequire-
ments of wearable devices, such as being flexible, compact and mechanically robust. Thus, the influence
of bending and crumpling deformations on the antenna Radio-frequency (RF) performance has been in-
vestigated. The simulated and measured results show that the proposed antenna functions satisfactorily
under smooth bending and crumpling conditions. However, for more severe deformation scenarios the
antenna presents a considerable performance degradation.
Finally, the Electromagnetic (EM) behaviour of this antenna has been examined in the vicinity of
a human upper arm. Regarding the computational simulations, four human arm models with different
geometric and dielectric properties have been presented. The antenna return loss, total efficiency, and
radiation patterns have been analysed for different antenna-body distances. Measurements with a real
human arm have also been carried out with the antenna placed 3 mm and 6 mm away from the human
arm.
Keywords:
Flexibleantenna,Ultra-Wideband(UWB),wearableapplications,returnloss,bend-
ing, crumpling.
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