الفهرس 
Chapter 1 IntroductionOnly 14 pages are availabe for public view
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Abstract
This thesis aims to solve the problem of the relative narrow bandwidth of the
branch-line coupler (BLC) and its relatively large size by taking the advantages of
the properties of the Composite Right/Left-handed metamaterials (CRLH) and its
duality (D-CRLH).
The following theoretical and practical investigations on conventional as
well as metamaterial two-section branch-line couplers are presented.
1. Starting with a detailed analysis of a two-section BLC with an arbitrary power
division ratio, closed-form expressions for the characteristic impedance of the
coupler arms and the scattering parameters were derived. The derived relations
are required for the designs of the proposed couplers.
2. Based on the derived relations, and the artificial transmission line concept, a
proposed 3 dB two-section BLC was designed, simulated, and fabricated using
the microstrip technology. The simulation was carried out using the Advanced
Design System (ADS) circuit simulator and the Computer Simulation
Technology (CST) electromagnetic simulator. The corresponding conventional
microstrip coupler was also designed and simulated for the sake of comparison.
3. Also, a proposed metamaterial (D-CRLH) two-section BLC was designed at a
frequency of 1.8 GHz, simulated, and fabricated. For this purpose, a D-CRLH Vshape coupled-line unit cell was suggested and analyzed. Then, unit cells for the
coupler arms were designed and simulated. A comparison between the simulated
and measured results of the proposed coupler was carried out.
4. The study was extended to apply the proposed metamaterial coupler into a
wideband balanced amplifier, which is a common microwave circuit component.
Therefore, a microwave transistor amplifier was also designed and simulated
using the ADS circuit simulator. The simulated results of this amplifier and the
balanced amplifier were obtained.