In this dissertation, some multi-function and flexible RF/microwave devices have been studied to solve the issues in the modern microwave system designs. First, a power divider with two functions is proposed. The first function is a zero-phase delay power divider using zero-phase impedance transformer. The second function is a power divider with impedance transforming property. To achieve the first function, the two arms are treated as zero-phase impedance transformers. When the phase requirement is relaxed, the second function is obtained. Shunt transmission line stubs are employed to connect the isolation resistor, which provides great flexibility in the design. Then, a balun with transparent termination impedance and flexible open arms is designed. The design parameters of the balun are independent to the port impedance. This property allows the balun to work with different system impedances. Furthermore, the two output ports of the balun do not need to be connected together, which enables the device to have a very flexible structure. Finally, the continuous research of a tunable/reconfigurable coupler with equal output impedance is presented. In addition to the tunable/reconfigurable responses, unequal output impedance property is added to the microstrip line coupler. To shrink the size at the low frequency and make it easy for fabrication at higher frequency, the coupler is redesigned using lumped components. To validate the design theories, simulations are carried out. Moreover, prototypes of the power divider and the balun are fabricated and characterized. The simulation and measurement results match well with the theoretical calculation.

Gamma-TiAl is an ordered intermetallic compound characterized by high strength to density ratio, good oxidation resistance, and good creep properties at elevated temperatures. However, it is intrinsically brittle at room temperature. This thesis investigates the potential for the use of grinding to process TiAl into useful shapes. Grinding is far from completely understood, and many aspects of the individual mechanical interactions of the abrasive grit with the material and their effect on surface integrity are unknown. The development of new synthetic diamond superabrasives in which shape and size can be controlled raises the question of the influence of those variables on the surface integrity. The goal of this work is to better understand the fundamentals of the abrasive grit/material interaction in grinding operations. Experimental, analytical, and numerical work was done to characterize and predict the resultant deformation and surface integrity on ground lamellar gamma-TiAl. Grinding tests were carried out, by analyzing the effects of grit size and shape, workpiece speed, wheel depth of cut, and wear on the subsurface plastic deformation depth (PDD). A practical method to assess the PDD is introduced based on the measurement of the lateral material flow by 3D non-contact surface profilometry. This method combines the quantitative capabilities of the microhardness measurement with the sensitivity of Nomarski microscopy. The scope and limitations of this technique are analyzed. Mechanical properties were obtained by quasi-static and split Hopkinson bar compression tests. Residual stress plots were obtained by x-ray, and surface roughness and cracking were evaluated. The abrasive grit/material interaction was accounted by modeling the force per abrasive grit for different grinding conditions, and studying its correlation to the PDD. Numerical models of this interaction were used to analyze boundary conditions, and abrasive size effects on the PDD. An explicit 2D triple planar slip crystal plasticity model of single point scratching was used to analyze the effects of lamellae orientation, material anisotropy, and grain boundaries on the deformation.

Thesis (M. App. Sc.)--Carleton University, 2004. / Includes bibliographical references (p. 112-118). Also available in electronic format on the Internet.

In recent years, tremendous growth of the wireless market can be defined through the following words: smartphone and high-data rate wireless communication. This situation gives new challenges to RF power amplifier design, which includes high-efficiency, multi-band operation, and robustness to antenna mismatch conditions. In addition to these issues, the industry and consumers demand a low-cost small-sized wireless device. A fully integrated single-chip CMOS transceiver is the best solution in terms of cost and level of integration with other functional blocks. Therefore, the effective approaches in a CMOS process for the abovementioned hurdles are highly desirable. In this dissertation, the new challenges are overcome by introducing adaptability to a CMOS power amplifier. Meaningful achievements are summarized as follows. First, a new CMOS switched capacitor structure for high power applications is proposed. Second, a dual-mode CMOS PA with an integrated tunable matching network is proposed to extend battery lifetime. Third, a switchless dual-band matching structure is proposed, and the effectiveness of dual-band matching is demonstrated with a fully-integrated CMOS PA. Lastly, a reconfigurable CMOS PA with an automatic antenna mismatch recovery system is presented, which can maintain its original designed performance even under various antenna mismatch conditions. Conclusively, the research in this dissertation provides various solutions for new challenges of advanced mobile terminals.