Novel Microstrip Fed Mechanically Tunable Combline Cavity Filter

Cataloged from PDF version of article.A novel configuration for mechanically tunable combline bandpass filters is proposed, where the classical resonating rod-tuning screw combination is replaced with a simple printed circuit-tuning screw combination. Moreover, because a printed circuit structure that uses metal vias forms the bottom part of the cavity, the coaxial type feeding and the coaxial to cavity matching of classical combline filters are also replaced with a microstrip feeding. Consequently, the proposed configuration provides smaller size, less weight, integration with other printed circuits and significant simplification in the fabrication process. A prototype filter is designed and fabricated for verification. The measured results are in good agreement with the simulation, and the filter exhibits very good harmonic suppression. © 2013 IEEE

Analysis of Input Impedance and Mutual Coupling of Microstrip Antennas on Multilayered Circular Cylinders Using Closed-Form Green’s Function Representations

Cataloged from PDF version of article.Closed-form Green’s function (CFGF) representations for cylindrically stratified media are developed and used in conjunction with a Galerkinmethod ofmoments (MoM)in the space domain for the analysis of microstrip antennas on multilayered circular cylinders. An attachment mode is used in the MoM solution procedure to accurately model the feeding of probe-fed microstrip antennas. The developed CFGF representations are modified in the source region (where two current modes can partially or fully overlap with each other during the MoM procedure) so that singularities can be treated analytically and hence, the proposed CFGF representations can be safely used in this region. Furthermore, accurate CFGF representations for the probe-related components (necessary for probe type excitations including the attachment mode) are obtained when the radial distance between the source and field points is electrically small or zero. Numerical results in the form of input impedance of various microstrip antennas and the mutual coupling between two antennas are presented showing good agreement when compared to the available published results as well as the results obtained from CST Microwave Studio

SIW based interdigital bandpass filter with harmonic suppression

Cataloged from PDF version of article.A novel configuration of interdigital bandpass filter based on the substrate integrated waveguide (SIW) technology is proposed. In addition to the interdigital resonators in SIW that determine the main response/characteristics of the filter, narrowing the width of the SIW at the center of the filter and additional vias at its input and output parts act as two additional control mechanisms to achieve the desired filter response. Moreover, dumbbells are etched to the ground side of the microstrip feeding sections at both ends of the filter to improve its harmonic suppression. A prototype filter is designed and fabricated for verification. The measured results are in good agreement with the simulations, and the filter exhibits very good harmonic suppression. (c) 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:66-69, 201

Failure of the Standard Coupled-Channels Method in Describing the Inelastic Reaction Data: On the Use of a New Shape for the Coupling Potential

We present the failure of the standard coupled-channels method in explaining the inelastic scattering together with other observables such as elastic scattering, excitation function and fusion data. We use both microscopic double-folding and phenomenological deep potentials with shallow imaginary components. We argue that the solution of the problems for the inelastic scattering data is not related to the central nuclear potential, but to the coupling potential between excited states. We present that these problems can be addressed in a systematic way by using a different shape for the coupling potential instead of the usual one based on Taylor expansion.Comment: 10 pages, 4 figures, 1 table, Latex:RevTex4 published in J. Phys. G: Nucl. Part. Phy

A fixed point iteration approach for analyzing the pull-in dynamics of beam-type electromechanical actuators

© 2020 Informa UK Limited, trading as Taylor & Francis Group. In this paper, a numerical approach is suggested to find a semi-analytical solution for the common nonlinear boundary value problems (BVPs) of cantilever-type micro-electromechanical system (MEMS) and nano-electromechanical system (NEMS) with a set of model parameters. The nonlinear BVPs that are studied involve the states of the single and double cantilever-shaped beams under the influence of Casimir and Van der Waals force for proper distances of separation. The method is based upon an integral operator that is formed considering Green’s function connected with the execution of Picard’s or Mann’s fixed point schemes. The numerical results for different cases of beam are presented and compared with those obtained by previous works to show the applicability, efficiency, and high accuracy of the suggested method

Closed-Form Green's Function Representations in Cylindrically Stratified Media for Method of Moments Applications

Cataloged from PDF version of article.Closed-form Green's function (CFGF) representations for cylindrically stratified media, which can be used as the kernel of an electric field integral equation, are developed. The developed CFGF representations can safely be used in a method of moments solution procedure, as they are valid for almost all possible source and field points that lie on the same radial distance from the axis of the cylinder (such as the air-dielectric and dielectric-dielectric interfaces) including the axial line (ρ = ρ′ and φ = φ′), which has not been available before. In the course of obtaining these expressions, the conventional spectral domain Green's function representations are rewritten in a different form so that i) we can attack the axial line problem and ii) the method can handle electrically large cylinders. Available acceleration techniques that exist in the literature are implemented to perform the summation over the cylindrical eigenmodes efficiently. Lastly, the resulting expressions are transformed to the spatial domain using the discrete complex image method with the help of the generalized pencil of function method, where a modified two-level approach is used. Numerical results are presented in the form of mutual coupling between two current modes to assess the accuracy of the final spatial domain CFGF representations. © 2009 IEE

Closed-Form Green's Function Representations for Mutual Coupling Calculations Between Apertures on a Perfect Electric Conductor Circular Cylinder Covered with Dielectric Layers

Cataloged from PDF version of article.Closed-form Green’s function (CFGF) representations are developed for tangential magnetic current sources to calculate the mutual coupling between apertures on perfectly conducting circular cylinders covered with dielectric layers. The new representations are obtained by first rewriting the corresponding spectral domain Green’s function representations in a different form (so that accurate results for electrically large cylinders, and along the axial line of a cylinder can be obtained). Then, the summation over the cylindrical eigenmodes is calculated efficiently. Finally, the resulting expressions are transformed to the spatial domain using a modified two-level generalized pencil of function method. Numerical results are presented showing good agreement when compared to CST Microwave Studio results

MR motility imaging in Crohn's disease improves lesion detection compared with standard MR imaging

Objective: To evaluate retrospectively in patients with Crohn's disease (CD) if magnetic resonance (MR) motility alterations correlate with CD typical lesions leading to an increased detection rate. Methods: Forty patients with histologically proven CD underwent MR enterography (MRE), including coronal cine sequences (cine MRE), in addition to the standard CD MR protocol. Two blinded readings were performed with and without cine MRE. Locations presenting motility alterations on the cine sequences were analysed on standard MRE for CD-related lesions. This was compared with a second reading using the standard clinical MRE protocol alone. Results: The number of lesions localised by cine MRE and identified on standard MRE compared with standard MRE alone were 35/24 for wall thickening (p = 0.002), 24/20 for stenoses (p = 0.05), 17/11 for wall layering (p = 0.02), 5/3 for mucosal ulcers (p = 0.02) and 21/17 for the comb sign (p = 0.05). Overall, cine MRE detected 35 more CD-specific findings than standard MRE alone (124/89; p = 0.007) and significantly more patients with CD-relevant MR findings (34/28; p = 0.03). Conclusion: CD lesions seem to be associated with motility changes and this leads to an increased lesion detection rate compared with standard-MRE imaging alon