<p><p>Microstrip structures became very attractive with the development of cost-effective dielectric materials. Among several techniques suitable to the analysis of such structures, the discrete mode matching method (DMM) is a full-wave approach that allows a fast solution to Helmholz equation. Combined with a full-wave equivalent circuit, the DMM allows fast and accurate analysis of microstrips lines on multilayered substrates.</p><p> </p><p>The knowledge of properties like dispersion and electromagnetic fields is essential in the implementation of such transmission lines. For this objective a MATLAB computer code was developed based on the discrete mode matching method (DMM) to perform this analysis.</p><p> </p><p>The principal parameter for the analysis is the utilization of different dielectric profiles with the aim of a reduction in the dispersion in comparison with one-layer cylindrical microstrip line, showing a reduction of almost 50%. The analysis also includes current density distribution and electromagnetic fields representation. Finally, the data is compared with Ansoft HFSS to validate the results.</p></p> / The German Aerospace Center has rights over the thesis work

Microstrip structures became very attractive with the development of cost-effective dielectric materials. Among several techniques suitable to the analysis of such structures, the discrete mode matching method (DMM) is a full-wave approach that allows a fast solution to Helmholz equation. Combined with a full-wave equivalent circuit, the DMM allows fast and accurate analysis of microstrips lines on multilayered substrates.   The knowledge of properties like dispersion and electromagnetic fields is essential in the implementation of such transmission lines. For this objective a MATLAB computer code was developed based on the discrete mode matching method (DMM) to perform this analysis.   The principal parameter for the analysis is the utilization of different dielectric profiles with the aim of a reduction in the dispersion in comparison with one-layer cylindrical microstrip line, showing a reduction of almost 50%. The analysis also includes current density distribution and electromagnetic fields representation. Finally, the data is compared with Ansoft HFSS to validate the results. / The German Aerospace Center has rights over the thesis work

No / This paper presents an investigation of the design optimization in microstrip lines to reduce the crosstalk level using Fuzzy Logic. In microstrip lines length and spacing, termination conditions of interconnection and output impedance of gates are the major components that cause crosstalk. In order to design high speed printed circuit board (PCB) with optimum interconnection configuration, it is essential to reduce the crosstalk to its minimum tolerance level. A design methodology is proposed to correlate electrical parameters and physical configuration of lines to the crosstalk phenomena. This design is subsequently optimized using Fuzzy Logic to reduce the level of crosstalk. A set of experiments is carried out to demonstrate the capabilities of the design and optimization methods. The effect of the geometrical configuration of the lines on crosstalk, particularly the spacing, is highlighted.

Full wave analysis of microstrip lines at microwave frequencies is performed by using method of moments in conjunction with closed-form spatial domain Green&rsquo / s functions. The Green&rsquo / s functions are in general Sommerfeld-type integrals which are computationally expensive. To improve the efficiency of the technique, Green&rsquo / s functions are approximated by their closed-forms. Microstrip lines are excited by arbitrarily located current sources and are terminated by complex loads at both ends. Current distributions over microstrip lines are represented by rooftop basis functions. At first step, the current distribution over a single microstrip line is calculated. Next, the calculation of the current distributions over coupled microstrip lines is performed. The technique is then, applied to directional couplers. Using the current distributions obtained by the analysis, the scattering parameters of the structures are evaluated by using Prony&rsquo / s method. The results are compared with the ones gathered by using simulation software tools, CNL/2&trade / and Agilent Advanced Design System&trade / (ADS).

In this thesis, an analysis technique for the slot coupled patch antennas using MoM in conjunction with the closed form Green&rsquo / s functions is presented. Slot coupled patch antennas are fed by a microstrip open stub which is coupled to the patch through an electrically small slot. Current distributions over the microstrip line, slot line and the patch are represented by rooftop basis functions. First, a relatively simple structure, microstrip coupled slot line is investigated using the proposed technique. Then the method is extended to the slot coupled patch antenna geometry. By using the method, current distributions on the feedline and the patch are calculated for a generic slot coupled patch antenna. Then by using the distributions, return scattering parameters of the antenna is approximated with complex exponentials using Prony&rsquo / s method. A parametric study is carried out to observe the effect of each antenna component on the antenna performance. Current distributions and return loss calculations are repeated for modified antennas to observe and demonstrate the performance differences. All simulations are verified using HFSS&reg / software and the results available in the literature.

Yes / A novel dual-polarized patch antenna for ultra-wideband (UWB) applications is presented. The antenna consists of a square patch and four capacitively coupled feeds to enhance the impedance bandwidth. Each feed is formed by a vertical isosceles trapezoidal patch and a horizontal isosceles triangular patch. The four feeds are connected to the microstrip lines that are printed on the bottom layer of the grounded FR4 substrate. Two tapered baluns are utilized to excite the antenna to achieve high isolation between the ports and reduce the cross-polarization levels. In order to increase the antenna gain and reduce the backward radiation, a compact surface mounted cavity is integrated with the antenna. The antenna prototype has achieved an impedance bandwidth of 112% at (|S11| ≤ -10 dB) whereas the coupling between the two ports is below -28 dB across the operating frequency range. The measured antenna gain varies from 3.91 to 10.2 dBi for port 1 and from 3.38 to 9.21 dBi for port 2, with a 3-dB gain bandwidth of 107%. / IEEE Antennas and Propagation Society

In recent years, the wireless industry has witnessed tremendous development for the defense and commercial segments. The explosive growth in the modern radio frequency and microwave systems leads to an increased interest in the research of miniaturized microwave circuits with superior performance. Broadband components, in particular band pass filters (BPFs) and couplers are some of the widely used components in the modern communication systems, software defined radios, cognitive radios, imaging systems and positioning radars. In order to meet these requirements, the use of innovative geometries, a thorough understanding of their behavior by appropriate analytical techniques and the use of appropriate fabrication approaches are essential. This thesis is an effort in this direction. In this thesis work, an aperture in the ground plane is used to achieve the tight coupling in the edge and broadside-coupled coupled lines which may be otherwise difficult due to the fabrication limitations. Since microstrip lines with an aperture in the ground plane are found to be very useful in various MIC and MMIC components, closed form analytical expressions developed here will be useful for their initial synthesis. The performances of components using these are enhanced using open/short circuited resonators, spurlines and stubs. A quasi-static approach has been investigated to obtain simple closed form expressions for a microstrip line with a rectangular aperture in the ground plane. The effect of a rectangular aperture in the ground plane has been incorporated in the commonly used expressions of a regular microstrip line by introducing the concept of an equivalent effective height. The expressions for the effective height microstrip geometries with defected ground are obtained and this has been further extended to various possibilities of two-conductor and three-conductor coupled lines. Analysis of the filters and the couplers are mainly based on the even and odd mode propagation characteristics of coupled lines. This approach is extended in this thesis for three conductor coupled lines. Novel broadband BPFs and couplers and dual band pass filters employing various coupled line configurations and defected ground have been developed in this research work. Most of these components have been implemented on a regular microwave laminate or LTCC medium (planar or multi-layer) and tested for the required RF performances. The experimental results were compared against the analytically computed results based on the circuit models and the full wave simulations using electromagnetic (EM) simulations for the validation. The results are in good agreement. With practical requirements of the organization in mind, additional design elements such as open circuit stubs have been incorporated in some of these designs to achieve the desired performance. It is expected that the wideband filter (3.0GHz to 3.8GHz) and the broadband coupler (4GHz to 6GHz) developed in this thesis work would be deployed in systems developed at the Central Research Laboratory, Bharat Electronics Limited, Bangalore, India. In summary, the present doctoral work strives to (i) establish a simplified analysis method for the microstrip lines and coupled microstrip lines with a rectangular aperture in the ground plane, (ii) extend the even and odd mode analysis of the coupled lines for several new coupled line configurations, (iii) design novel broadband microwave filters, dual band filter and couplers using both these, (iv) fabricate these devices using the planar technologies including LTCC, and (v) validate the analysis and design with important practical applications.

An analysis using numerical methods can calculate electrical and construction characteristics parameters of microwave devices quite accurately. However, numerical methods require a lot of computation resources and time for calculations to be made. Rapid perfection of the computer technologies and software with implementation of the numerical methods has laid down the conditions to the rapid design of the microwave devices using computers. / Disertacijoje nagrinėjamos mikrobangų įtaisų analizės ir sintezės proble-mos, taikant lygiagrečiąsias kompiuterines sistemas. Pagrindiniai tyrimo objektai yra daugialaidės mikrojuostelinės linijos ir meandrinės mikrojuostelinės vėlinimo linijos. Šie objektai leidžia perduoti, sinchronizuoti bei vėlinti siunčiamus signalus ir yra neatsiejama dalis daugelio mikrobangų prietaisų. Jų operatyvi ir tiksli analizė bei sintezė sąlygoja įtaisų kūrimo spartinimą. Pagrindinis disertacijos tikslas – sukurti lygiagrečiąsias metodikas ir algoritmus, skirtus sparčiai ir tiksliai atlikti minėtų linijų analizę ir sintezę. Sukurtų algoritmų ir metodikų taikymo sritis – mikrobangų įtaisų modeliavimo ir automatizuoto projektavimo progra-minė įranga.

Disertacijoje nagrinėjamos mikrobangų įtaisų analizės ir sintezės proble-mos, taikant lygiagrečiąsias kompiuterines sistemas. Pagrindiniai tyrimo objektai yra daugialaidės mikrojuostelinės linijos ir meandrinės mikrojuostelinės vėlinimo linijos. Šie objektai leidžia perduoti, sinchronizuoti bei vėlinti siunčiamus signalus ir yra neatsiejama dalis daugelio mikrobangų prietaisų. Jų operatyvi ir tiksli analizė bei sintezė sąlygoja įtaisų kūrimo spartinimą. Pagrindinis disertacijos tikslas – sukurti lygiagrečiąsias metodikas ir algoritmus, skirtus sparčiai ir tiksliai atlikti minėtų linijų analizę ir sintezę. Sukurtų algoritmų ir metodikų taikymo sritis – mikrobangų įtaisų modeliavimo ir automatizuoto projektavimo progra-minė įranga. / An analysis using numerical methods can calculate electrical and construction characteristics parameters of microwave devices quite accurately. However, numerical methods require a lot of computation resources and time for calculations to be made. Rapid perfection of the computer technologies and software with implementation of the numerical methods has laid down the conditions to the rapid design of the microwave devices using computers.

Dielectric High-frequency transmission lines are natural alternative to the lines made of metal in term of low loss. These lines are mainly used in microwave techniques of measuring. The main object is to describe basic parameters of metal and dielectric transmission lines and their comparison. Next point is a basic overview of the excitation the lines from metal and it's application on dielectric transmission lines. Then make the simulation of microstrip directional couplers and coupler made by dielectric waveguides. The last point of work is construction these directional couplers and measuring their most important parameters.