19 research outputs found
Dual band filter design using real frequency technique and frequency transformation
In this work, we present a frequency transformation based dual-band filter design approach using scattering based real frequency technique. In the design process, conventional low-pass to band-pass frequency transformation is integrated with the simplified real frequency technique to construct double pass-band filters. The approach is particularly advantageous for designing matching filters between different termination resistances. As an alternative to a direct low-pass to dual-band frequency transformation, the use of dual-band mapping on a normalized band-pass prototype is investigated for efficient control of the passbands. Application of the proposed approaches for dual-band filters is presented by comparative design examples.Publisher's Versio
Development of waveguide filter structures for wireless and satellite communications
This thesis explores the possibilities of the design and realization of compact conventional and substrate integrated waveguide structures with improved performance taking advantage of recent cross-coupled resonator filters theory achievements such as the modular filter design approach using non-resonating nodes and inline extracted pole filters. Therefore, the core of the thesis presents the following stages of work:
-- Solution of electromagnetic problem for wave propagation in rectangular
waveguide structures; overview of substrate integrated waveguides.
-- Review of available design procedures for cross-coupled resonator filters;
realization of coupling matrix synthesis methods by optimization.
-- Investigation of the possibility to implement filtering modules using E-plane metallo-dielectric inserts in conventional rectangular waveguides. Application of the modules in configurations of bandpass and dual-band filters. Experimental
verification of the filters.
-- Implementation of inline extracted pole filters using E-plane inserts in
rectangular waveguides. Use of generalized coupling coefficients concept for
individual or coupled extracted pole sections. Development of new extracted
pole sections. Application of the sections in the design of compact cross-coupled filters with improved stopband performance.
-- Application of the techniques developed for conventional rectangular
waveguides to substrate integrated technology. Development of a new negative
coupling structure for folded substrate integrated resonators. Design of improved modular and extracted pole filters using substrate integrated waveguides
Modern Observational Techniques for Comets
Techniques are discussed in the following areas: astrometry, photometry, infrared observations, radio observations, spectroscopy, imaging of coma and tail, image processing of observation. The determination of the chemical composition and physical structure of comets is highlighted
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Computational automation for efficient design of acoustic metamaterials
Acoustic metamaterials (AMMs) are an exciting technology because they are capable of responding to vibrations in ways that are impossible to achieve with conventional materials. However, realization of AMMs requires engineering design to provide a connection between first-principles research and production of parts that perform as expected. Designing AMMs is a challenging endeavor because evaluating designs is costly and manufacturing metamaterials requires precise techniques with small minimum resolutions. To address these challenges, new computational tools are necessary to aid design. This work proposes three tasks that improve the capabilities of design for AMM while being extensible to other engineering design automation tasks. The first task is to develop a design exploration tool that improves the computational efficiency of identifying sets of high-performing designs in a design space that is sparse and comprises mixed discrete/continuous data. The second task is to develop a process for designers to evaluate manufacturability of difficult-to-manufacture parts and drive co-development of manufacturing methods and AMM. In the final task, a machine learning based method is developed to efficiently model AMM with heterogeneous arrangements of their microstructures such that strict homogenization is infeasible. The outcomes from completing these tasks will provide a significant and novel improvement over existing methods of designing AMMs.Mechanical Engineerin
Brain and Human Body Modeling
This open access book describes modern applications of computational human modeling with specific emphasis in the areas of neurology and neuroelectromagnetics, depression and cancer treatments, radio-frequency studies and wireless communications. Special consideration is also given to the use of human modeling to the computational assessment of relevant regulatory and safety requirements. Readers working on applications that may expose human subjects to electromagnetic radiation will benefit from this book’s coverage of the latest developments in computational modelling and human phantom development to assess a given technology’s safety and efficacy in a timely manner. Describes construction and application of computational human models including anatomically detailed and subject specific models; Explains new practices in computational human modeling for neuroelectromagnetics, electromagnetic safety, and exposure evaluations; Includes a survey of modern applications for which computational human models are critical; Describes cellular-level interactions between the human body and electromagnetic fields
Spin dynamics in semiconductors
This article reviews the current status of spin dynamics in semiconductors
which has achieved a lot of progress in the past years due to the fast growing
field of semiconductor spintronics. The primary focus is the theoretical and
experimental developments of spin relaxation and dephasing in both spin
precession in time domain and spin diffusion and transport in spacial domain. A
fully microscopic many-body investigation on spin dynamics based on the kinetic
spin Bloch equation approach is reviewed comprehensively.Comment: a review article with 193 pages and 1103 references. To be published
in Physics Reports
Multiband and Concurrent Matching Network Design via Brune Sections
A general multiband matching network design methodology for complex load impedance terminations is presented. In the proposed approach, Real Frequency Techniques (RFT) are used to define and optimize the multiband matching network. In the characterization of the multiband network, multiple notch bands are obtained by the employment of finite transmission zeros (FTZ) in the transfer function. Brune section realization of finite transmission zeros and the associated coupled coil free realizations are discussed. A triple band matching network design for a triple band Sierpinski antenna load is presented to illustrate the performance of the proposed approach
Multiband and concurrent matching network design via brune sections
A general multiband matching network design methodology for complex load impedance terminations is presented. In the proposed approach, Real Frequency Techniques (RFT) are used to define and optimize the multiband matching network. In the characterization of the multiband network, multiple notch bands are obtained by the employment of finite transmission zeros (FTZ) in the transfer function. Brune section realization of finite transmission zeros and the associated coupled coil free realizations are discussed. A triple band matching network design for a triple band Sierpinski antenna load is presented to illustrate the performance of the proposed approach.Publisher's Versio