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Novel microwave and millimeterwave (mm-wave) bandstop filters using artificial periodic substrate electromagnetic bandgap (EBG) are investigated in this paper. Three types of microstrip structures using periodically modified trace width, patterned dielectric substrate, and periodically modified ground plane are treated, respectively. By periodically modifying either the width of the conductor trace, the substrate height, or the dielectric constant of a standard microstrip transmission line, it has been possible to design microwave bandstop filter functions with wide stopband characteristics and reduced size, compared to conventional microwave lRF filter structures. Commercial electronic design automation (EDA) and computational electromagnetic tools such as Agilent's advanced design system (ADS) and CST Microwave Studio are used in the design and simulations of these filter structures. The effects of the physical parameters of the structures on the filter characteristic are studied. The design procedure and simulation results are described and possible applications of these filter structures are discussed in this paper. A particularly wide stopband is achieved by the circuits presented in this paper, which use only a few cell elements. A significant performance improvement of microstrip patch antenna has been observed by implementing one of the presented EBG periodic substrate structures. [ABSTRACT FROM AUTHOR]

High-frequency transmission lines crosstalk reduction using spacing rules is treated in this paper. Two of the most popular planar transmission line configurations, namely microstrip and stripline, commonly used in printed circuit boards and radio frequency/microwave integrated circuits, are considered in this work. The trace separation between two adjacent transmission lines of each type is stepwise increased as function of the trace width. The single-ended transmission line structures are numerically investigated by a frequency-based 3-D full-wave electromagnetic analysis tool. A particular case using coated microstrip transmission lines has been fabricated, along with some calibration structures, to allow direct measurement and experimental analysis of crosstalk between the single-ended transmission lines. The test structures are characterized at high-frequency (up to 20 GHz) with scattering parameters using a vector network analyzer. The experimental results are compared with the simulation data, and some conclusions and suggestions on the impact and use of spacing rules for high-frequency crosstalk reduction between single-ended transmission lines are presented. These investigations emphasize the necessity of reevaluating classical design rules for their suitability in high-frequency applications. [ABSTRACT FROM AUTHOR]

In this paper, the problem of using guard traces for reducing crosstalk between differential transmission line pairs is investigated, both experimentally and by full-wave electromagnetic (EM) simulations. Different cases of differential lines crosstalk are treated with and without guard trace separation between the differential line pairs. Coated microstrip printed circuit board test structures including thru-reflect-line calibration standards are designed and fabricated on a high frequency laminate material, allowing direct measurement of crosstalk between adjacent differential line pairs in the absence and in the presence of guard traces stitched with vias of regular spacing. The test structures are characterized with mixed-mode scattering parameters using a physical layer test system. Different configurations (of differential line pairs) without guard trace, with floating guard traces (which are terminated and nonterminated) and with a solid guard trace separation are investigated using a High Frequency Structure Simulator (a commercial full-wave 3-D EM simulation tool). The experimental data are compared with the simulation results, and some conclusions and guidelines on the effect of guard traces for alleviating crosstalk between differential transmission lines are presented. [ABSTRACT FROM AUTHOR]