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|Issue Date: ||30-Jan-2014|
|Authors: ||Leonardi, Ornella|
|Title: ||Circularly polarized antennas|
|Abstract: ||In recent years low profile, lightness, compactness, easy manufacturing
and integrability with solid-state devices on a circuit board have become a
priority in the antenna design. Microstrip antennas are a possible answer
to these new requirements in several areas, such as remote sensing, mobile satellite and cellular communications, direct broadcast satellite (DBS)
system and global positioning system (GPS).
Many of the above mentioned applications make use of circularly polarized
antennas. However, such requirement in planar microstrip antenna
is not a trivial task since many factors have to be considered including
fabrication tolerance and systematic errors in the manufacturing process.
In the present thesis we address the task to achieve circular polarization
with very compact planar antennas in two ways:
1) a more conventional one dealing with two innovative designs;
2) a less conventional one through of artificial materials, such as High
Impedance Surface (HIS).
As far as the first point is concerned, two standard designs have been
developed for a Dedicated Short Range Communication (DSRC) system.
In particular, we have proposed two innovative compact antennas that
represent a step forward with respect to other available DSRC solution.
The two proposed antenna prototypes have been optimized, fabricated
and experimentally tested. They represent an answer to the need of
achieving good circular polarization antennas in a small mobile On-Board
Unit (OBU) of a DSRC system.
As a further study, we have considered to improve performance such
as the radiated power, the gain and the directivity, or to reduce the global
antenna thickness. For this reason we have developed a full-wave model
for periodic surface and considered their employment to achieve circular
polarization. As a proof of concept, we have tested a simple arrangement
that allows circular polarization of the radiated field.
The thesis is organized as follows.
In the first part, we briefly introduce some relevant technical features
of microstrip antenna s. Then the properties of circular polarized waves
are discussed, with particular interest in wireless communications. The
circular polarization quality factors and antenna measurement setup are
briefly introduced and discussed.
In the second part, we address the design and the experimental characterization of two circularly polarized microstrip patch antenna prototypes.
In the last part of the thesis, High Impedance Surfaces (HIS) are
briefly introduced. Then, a simple FEM-model is presented and compared
with the standard FTDT-model used in literature. In this respect,
a rectangular-array-patch working as HIS surface is considered and tested
to achieve circular polarization with a printed dipole.|
|Appears in Collections:||Area 09 - Ingegneria industriale e dell'informazione|
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|LNRRLL81H69C351F-Ornella_Leonardi.pdf||Thesis_Ornella_Leonardi||6,48 MB||Adobe PDF||View/Open
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