Broadband Feed for a Parabolic Antenna for Satellite Tracking

104 Pages·2011·2.96 MB·Portuguese

Faculdade de Engenharia da Universidade do Porto

Broadband Feed for a Parabolic Antenna for
Satellite Tracking
Frederico José Teixeira Moreira
Final Version
MSc Thesis developed in the scope of the
Integrated Master in Electrical and Computers Engineering
Telecommunications Major
Supervisor: Sérgio Reis Cunha (PhD)

January 2011
© Frederico José Teixeira Moreira, 2011
Resumo
Actualmente, o processo de telecomunicações no mundo inteiro requer transmissões
rápidas e baratas. Obedecendo a isso, as antenas de banda larga são parte da solução para
estabelecer um conceito de utilização de extensas larguras de banda às altas frequências.
Deste modo, os sistemas de satélite têm muitas potencialidades para tornar o mundo numa
pequena aldeia global. Como exemplo, os satélites de hoje servem a humanidade em áreas
tão extensas como a navegação ou a meteorologia.
Tendo em conta o referido, a pesquisa efectuada nesta tese é centrada na implementação
de uma antena espiral equiangular e planar, capaz de alimentar uma antena parabólica de
forma coerente. De facto, ela reúne várias características que são importantes para alimentar
correctamente uma antena parabólica, a fim de permitir uma comunicação estável com os
satélites que se pretende monitorizar. Tal antena é também conhecida como uma antena de
banda larga, que é caracterizada por parâmetros vitais como a relação de ondas estacionárias
(VSWR), impedância de entrada, padrão de radiação, coeficiente de reflexão, entre outros.
Por fim, as medições dos parâmetros da antena espiral equiangular e planar, foram feitas
com a ajuda de programas de simulação (Ansoft HFSS), sendo posteriormente comparadas
com resultados experimentais obtidos no analisador de rede vectorial e na câmara anecóica.

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Abstract
Currently, world telecommunications require fast and cheap transmissions. Concerning to
that, broadband antennas are part of the solution to establish a concept of wideband
frequency usage. Thus, satellite systems have many potentialities to make the world a small
global village. As an example, satellites of nowadays can serve humankind in such areas as
navigation or weather forecast.
Concerning to that, the research of this thesis is focused on the implementation of a
planar equiangular spiral antenna, which can gather several characteristics that are
important to feed properly a parabolic antenna, in order to enable a good communication
with satellites that can be tracked. Such antenna is a broadband antenna that is
characterised by vital parameters as voltage standing wave ratio, input impedance, radiation
pattern, reflection coefficient, between others.
Finally, the measurements of those antenna parameters were made using software
simulation (Ansoft HFSS) and were compared to experimental results obtained from an
anechoic chamber and from a vector network analyser.
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Acknowledgements
I am pleased to acknowledge the advice and ideas of Professor Sérgio Reis Cunha, to
whom must be endorsed all the credit for the imaginative notions leading to the design of
equiangular spiral antenna. It was a pleasure to work with such a dedicated person.

I want to thank my friends Mário Pereira and Qi Luo for the help they provided me.

I must also acknowledge André Vidal and André Paiva, without whose motivation and
encouragement I would not finish my thesis on time.

I would like to express my sincere gratitude to all my friends and family, especially to
Eduardo Magalhães for all the support during my entire thesis, and to my best friend Tó Zé
who was always encouraging me all the time.

And finally, infinite thanks to my purple cat who was always with me.

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"Happiness is always there; where you look for it."
Unknown Author

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