الفهرس 
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Abstract
Abstract
This thesis is to propose novel generic methodology and design
equations to design multi-band bandpass filters. The design procedure utilizes an
approach based on asymmetric half-wavelength resonators. The obtained
optimized filters by this approach are used as reference designs and proposed
technique is applied to calculate the new filter physical parameters that satisfy
its given specifications. Dual-band, tri-band and quad-band filters are designed
and implemented using this novel transformation technique. This technique is
easy, fast, generic and accurate without relying on computer aided design
(CAD) optimization.
A reference dual-band filter is designed, based on asymmetric halfwavelength resonator, to obtain the following specifications: the insertion loss is
better than 1.5 dB and return loss is better than 10 dB, bandwidths, BW
1
≥ 60
MHz and BW2
≥ 150 MHz at the resonance frequencies, fr1 = 2.1 GHz and fr2
=
5.6 GHz for UMTS / WiMAX applications, respectively. Utilizing this reference
filter; two dual-band filters for GPS / WLAN and GPS / WiMAX applications
are illustrated to verify the proposed novel generic design equations. The results
obtained from measurements agree well with that obtained from simulations,
which verifies the proposed method.
A reference tri-band filter is designed, based on asymmetric halfwavelength resonator, to obtain the following specifications: the insertion loss is
better than 3 dB and return loss is better than 10 dB, at f
r1 =1.4 GHz, fr2
= 4 GHz
and f
r3 = 6.3 GHz for L-Band DAB, Radar (G-band) and Radar (C-band)
applications, respectively. In addition, two tri-band filters are designed to verify
the proposed novel generic transformation and design equations based on the
reference filter. The proposed technique is validated through fabricating one of
the designed examples. The results obtained measurements agree well with that
obtained from simulations.
Finally, the same procedure is repeated for quad-band filters. All results
are obtained using circuit and momentum simulations of the Advanced Design
System (ADS) from Agilent (Now, Keysight Technologies). A set of prototypes
are fabricated and experimentally verified using RT 5880 substrate with
thickness, h = 0.787 mm, relative dielectric constant, εr
= 2.2 and loss tangent,
tan = 0.0009. The performance characteristics have been measured using the
Rohde & Schwarz ZVB20 4-port vector network analyzer.
This thesis is organized in five chapters described as follows: the
problem statement, the approach to its solution and thesis organization are
introduced in Chapter 1. Basic concepts and theories that form the foundation
for multi-band microstrip filter design are described in Chapter 2. Chapter 3
provides the analysis and design steps of dual-band filter using asymmetric halfwavelength resonators structure with shunt open stubs. The novel transformation
and design equations are introduced. The proposed systematic dual-band filter
procedure is applied to implement sample filters with desired specifications. The
same approach for tri-band and quad-band filters is repeated and verified in
Chapter 4. Chapter 5 draws the conclusions obtained from this research and
provides recommendations for the future work.
Key words: RF Filters, Multi-band Filters, Modern wireless systems,
Asymmetric half-wavelength resonators or Microstrip Filters.