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|Title: ||Innovative passive microwave components for wireless communication|
|Other Titles: ||Ying yong yu wu xian tong xun zhi chuang xin bei dong wei bo yuan jian|
|Authors: ||Cheung, King Yin (張經賢)|
|Department: ||Department of Electronic Engineering|
|Degree: ||Master of Philosophy|
|Issue Date: ||2010|
|Publisher: ||City University of Hong Kong|
|Subjects: ||Microwave devices.|
Microwave communication systems.
|Notes: ||CityU Call Number: TK7876 .C497 2010|
vii, 79 leaves : ill. 30 cm.
Thesis (M.Phil.)--City University of Hong Kong, 2010.
Includes bibliographical references (leaves 72-75)
|Abstract: ||Nowadays, there are many wireless services in the market such as WiFi, WiMAX, GSM and
WCDMA whose services when combined into a single wireless unit are advantageous such
as those found in access points. These services have different operating bands and follow
different standards. Therefore, there is a need to study universal wireless components that is
transparent to both multi-band and multi-standard operation. Multi-band with multifunction is
usually required in these systems to reduce cost. In addition, a single circuit performing
multiple functions and operating at multiple bands occupy smaller circuit area and possesses
lower insertion loss.
Two types of important microwave components are investigated in this thesis. By using
various kinds of technique, those components can operate in multiple bands or provide two
First, two new Quadrature hybrid coupler designs are introduced. Quadrature couplers which
provide equal power division and 90 degree phase difference between their two outputs is one
of the key components found in wireless communication systems with a wide range of
A dual-band branch-line quadrature coupler with extended bandwidth using simple threesection
branch line is presented. This design exhibits larger bandwidth than existing dualband
designs reported in previous literatures. A dual-band branch line coupler was designed
and measured to give 34.5% and 16.4 % bandwidth in the lower band and upper band
respectively with amplitude imbalance less than 1dB. The achieved bandwidth is wide
enough to cover wireless local area network (WLAN) and Wideband Code Division Multiple
Access (WCDMA) applications.
A dual-band hybrid coupler with source to load impedance transformation is also presentwith
detailed design formulas. In previous literatures, couplers were either dual band or impedance
transforming but not both.
Antenna used for transmitting and receiving signal over the air is another important
component found in wireless communication. In order to address the requirement for modern RF front-ends, Antennas needs to be compact in size and able to operate in multiple
frequencies. Frequency Reconfigurable antennas with out-of-band rejection without the use
of filters have found favor as a solution for the universal wireless Transceiver due to the
omission of the filter and superior antenna performance. In this thesis, a new design of a Toploaded
Monopole based on fractal geometry with electronic switching of the operating bands
Components presented in this work can be applied to reduce the total number of elements
found in modern wireless units. Consequently, lower insertion loss and smaller circuit size
can be achieved.|
|Online Catalog Link: ||http://lib.cityu.edu.hk/record=b3947835|
|Appears in Collections:||EE - Master of Philosophy |
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