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|Title: ||Patch type circuits for wireless communications|
|Other Titles: ||Yong yu wu xian tong xun de tie pian xing dian lu|
|Authors: ||Zheng, Shaoyong ( 鄭少勇)|
|Department: ||Department of Electronic Engineering|
|Degree: ||Doctor of Philosophy|
|Issue Date: ||2011|
|Publisher: ||City University of Hong Kong|
|Subjects: ||Wireless communication systems.|
|Notes: ||CityU Call Number: TK5103.2 .Z438 2011|
xv, 147 leaves : ill. 30 cm.
Thesis (Ph.D.)--City University of Hong Kong, 2011.
Includes bibliographical references.
|Abstract: ||Microstrip patch elements are used in wireless communication systems for its
well-known advantages that include ease of construction, strong mechanical structure,
low profile, and low cost. However, its relatively large size and narrow bandwidth limits
its practical applications. This thesis covers different approaches to solve these technical
challenges. These approaches each provide the detailed design guidelines for existing
configurations, and can be used to develop new components to extend their potential.
First of all, to compress the bulky size of patch elements, a patterned ground plane
structure is proposed and verified. Four different patterns are etched into the ground
plane to reroute the current distribution in the patch, and they all achieve different size
reductions and with different complexity. For demonstration purposes, the patterned
ground plane structure is applied to a four port network, rectangular patch hybrid
coupler, achieving a significant size reduction of up to 72.3% compared to the
In addition, the patterned ground plane structure is proposed and verified to achieve
frequency agility in the solution of the narrow bandwidth problem. An auxiliary patch is
introduced into the patterned ground plane as a mechanism for changing the
characteristic of the patch element, to realize frequency agility. This is achieved because
the capacitance between the upper patch and ground plane can be controlled by loading
tunable capacitors via the auxiliary patch. A frequency agile rectangular patch hybrid
coupler with varactor loaded patterned ground plane is designed to operate over a
frequency range of 50% with good return loss, small amplitude imbalance and
quadrature phase characteristics.
Besides the frequency agile approach, the broad band slot coupled structure is employed
as one of the most straightforward way to solve the problem with bandwidth. The
vertically installed slot coupled patch is proposed as an alternative to implement
broadband characteristics with uniplanar topology. The pattern on the ground plane underneath the vertical substrate is introduced to enhance the coupling strength,
increase the design freedom, and compress the circuit height. To demonstrate its simple
structure and good performance compared with previous coupled line structures, the
design of broadband 3 dB quadrature coupler and a broadband differential phase shifter
will be demonstrated.
Integrating multiple functions within a simple patch element is another proposed
method for the size reduction of patch elements. Out of phase equal power division and
bandpass filter characteristics are combined within one patch element. The novelty of
the proposed structure is to use simple asymmetric cross slots in the patch element to
achieve this integration. Coplanar waveguide/microstrip broadside coupling is then
investigated to enhance the performance of the patch balanced filter and eliminate
narrow coupling gaps and microstrip lines. Subsequently, transition between microstrip
and coplanar waveguide is then added to the patch element by targeting certain
electromagnetic coupling methods for higher level integration without introducing
|Online Catalog Link: ||http://lib.cityu.edu.hk/record=b4086778|
|Appears in Collections:||EE - Doctor of Philosophy |
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