Analysis of the dispersion characteristics in periodic Substrate Integrated Waveguides

In this work, we study the dispersion characteristics of the first modes of four periodic structures implemented in Substrate IntegratedWaveguide (SIW) technology. Two kind of topologies (based on inductive irises and on rectangular air holes) and two kind of symmetries (normal reflection and glide symmetry) are studied by using electromagnetic simulation software. The obtained results show relevant differences in the characteristics of passbands and stopbands between glide-symmetric and non-glide-symmetric structures. The dispersion characteristics of the first propagating mode are analyzed for finite implementations of all the studied structures. Furthermore, the finite implementations of the structures based on inductive irises have been fabricated and measured, showing good agreement with the simulation results.This research was supported by the Ministerio de Ciencia e Innovación, Spanish Government , under R&D Project PID2019-103982RB-C43

Low-cost Implementation of a Waveguide-based Microwave Filter in Substrate Integrated Waveguide (SIW) Technology

This paper presents the design and practical implementation of a waveguide-based microwave filter in Substrate Integrated Waveguide (SIW) technology. The use of SIW technology for implementing waveguide filters makes the presented design specially aimed for being used in undergraduate courses related to microwave engineering and filter designing. Their low cost and easiness from the filter fabrication point of view allows their use in microwave laboratory courses where students can implement their own theoretical filter designs and measure their frequency response. The requiring mechanics in the manufacturing of microwave filters in waveguide technology (both rectangular and circular) makes its use practically unfeasible in academic laboratories because of its cost. For this reason, a practical design example of a waveguide iris filter using the impedance inverter model is proposed in this paper for academic laboratories, using SIW technology. This is a low cost and easy to manufacture technology. The overall process includes the design of the ideal band-pass prototype filter using the impedance inverter and its implementation in an inductive iris-coupled waveguide filter, by using a developed electromagnetic simulator based on the mode-matching technique. Finally, the equivalent filter in SIW technology is obtained and optimized by using HFSS simulator, including a SIW to microstrip transition. A prototype of the designed filter has been fabricated and measured, showing a good agreement between measurements and simulations.Ministerio de Economía y Competitividad, TEC2013-47037-C5-4-R

Multilayered additive-manufactured half-wavelength coupled line filters

This work presents the design, fabrication and measurements of third-order multilayered filters by additive manufacturing technology. The filters are fabricated using conventional half-wavelength line resonators and a low-cost 3d polylactic acid polymer additive manufacturing process, which allows rapid prototyping and fabrication of complex topologies. The designs, performed at a centre frequency of 2.0 GHz, aim to provide fast manufacturing and get enhanced performances when compared to conventional coupled line third order filters using microstrip technology on commercial substrates. The simulated and measured responses of the fabricated prototypes are in all cases in good agreement

Electron Emission of Pt: Experimental Study and Comparison With Models in the Multipactor Energy Range

"(c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works."Experimental data of secondary emission yield (SEY) and electron emission spectra of Pt under electron irradiation for normal incidence and primary energies lower than 1 keV are presented. Several relevant magnitudes, as total SEY, elastic backscattering probability, secondary emission spectrum, and backscattering coefficient, are given for different primary energies. These magnitudes are compared with theoretical or semiempiricalThis work was supported in part by the Ministerio de Economia y Competitividad under Project TEC2013-47037-C5-4-R, and in part by MICIIN through the Space Programme under Project AYA2012-39832-C02-01/02. The review of this paper was arranged by Editor M. Thumm.Bronchalo, E.; Coves, A.; Mata Sanz, R.; Gimeno Martinez, B.; Montero, I.; Galán, L.; Boria Esbert, VE.... (2016). Electron Emission of Pt: Experimental Study and Comparison With Models in the Multipactor Energy Range. IEEE Transactions on Electron Devices. 63(8):3270-3277. https://doi.org/10.1109/TED.2016.2580199S3270327763

A novel band-pass filter based on a periodically drilled SIW structure

The design and fabrication of a band-pass step impedance filter based on high and low dielectric constant sections has been realized on substrate integrated waveguide (SIW) technology. The overall process includes the design of the ideal band-pass prototype filter, where the implementation of the impedance inverters has been carried out by means of waveguide sections of lower permittivity. This can be practically achieved by implementing arrays of air holes along the waveguide. Several SIW structures with and without arrays of air holes have been simulated and fabricated in order to experimentally evaluate their relative permittivity. Additionally, the equivalent filter in SIW technology has been designed and optimized. Finally, a prototype of the designed filter has been fabricated and measured, showing a good agreement between measurements and simulations, which demonstrates the validity of the proposed design approach.This work was supported by the Ministerio de Economía y Competitividad, Spanish Government, under the Research Project TEC2013-47037-C5-4-R

Analysis of Multipactor Effect in a Partially Dielectric-Loaded Rectangular Waveguide

This paper 1 presents a study of the multipactor 2 effect in a partially dielectric-loaded rectangular waveguide. 3 To obtain the simulations presented in this paper, a detailed 4 analysis of the dynamics of the electron inside this waveguide 5 has been performed, taking into account the radio frequency 6 electromagnetic fields propagating in the waveguide and the dc 7 electric field that appears because of the charging of the dielectric 8 layer. This electrostatic field is obtained by computing the electric 9 potential produced by an arbitrary charge distribution on the 10 dielectric layer in a dielectric-loaded waveguide. The electron 11 trajectory is then found by numerically solving the equations of 12 motion. The results obtained show that multipactor discharges 13 do turn off by themselves under certain circumstances when they 14 occur in such dielectric-loaded waveguide.10.13039/5011000110033-Agencia Estatal de Investigación; Unión Europea through the Fondo Europeo de Desarrollo Regiona

Experimental Study of the Multipactor Effect in a Partially Dielectric-Loaded Rectangular Waveguide

This letter presents the experimental study of the multipactor threshold in a partially dielectric-loaded rectangular waveguide, whose results validate a multipactor model recently developed by the authors, which includes the charge distribution appearing on the dielectric surface during the multipactor discharge. First, the variation of the multipactor RF voltage threshold has been theoretically analyzed in different waveguide configurations: in an empty waveguide, and also in the cases of a one-sided and two-sided dielectric-loaded waveguides. To reach this aim, an in-house Monte Carlo simulation tool has been developed. The Secondary Electron Yield (SEY) of the metallic and dielectric materials used in the numerical simulations have been measured experimentally. Finally, an aluminum WR-75 symmetric E-plane rectangular waveguide transformer has been designed and fabricated, in which several multipaction tests have been carried out to validate the in-house software tool, demonstrating an excellent agreement between the simulation results and the experimental data.This work was supported by the Agencia Estatal de Investigaci´on (AEI) and by the Uni´on Europea through the Fondo Europeo de Desarrollo Regional - FEDER - “Una manera de hacer Europa” (AEI/FEDER, UE), under the Research Projects TEC2016-75934-C4-2-R and TEC2016-75934-C4-1-R

Bandpass filters based on periodic structures in SIW technology

In this work, the study of two different topologies of S-band band-pass filters based on periodic structures in substrate integrated waveguide (SIW) technology is theoretical and experimentally addressed. The first topology consists of periodic rectangular perforations of the SIW substrate. In this filter topology, the lower cutoff frequency is determined by the cutoff frequency of the first Floquet mode of the periodic structure, while the upper cutoff frequency and the rejection band are conditioned by its first band-gap. The second topology consists of a periodic array of square complementary split-ring resonators (CSRRs) etched on the waveguide surface. In this case, the use of subwavelength resonators with evanescent-wave transmission leads to a much smaller filter, given that the pass-band is below the cutoff frequency of the waveguide. The effect of the different dimensions of the unit cell in the filters characteristics (lower cutoff frequency, pass-band, and rejection-band associated to the first band-gap of the periodic structure) is analyzed through the dispersion diagram of the periodic cell. Finally, two band-pass filters based on each topology have been designed and built, showing in both cases good matching and low insertion loss in the pass-band, and a deep rejection band.This work was supported by the Agencia Estatal de Investigaci´on (AEI) and by the Uni´on Europea through the Fondo Europeo de Desarrollo Regional - Una manera de hacer Europa (AEI/FEDER, UE), under the research project TEC2016-75934-C4-2-R

Multispurious suppression in parallel-coupled line filters by means of coupling control

In this work, a new method for stopband extension in both open-ended and interdigital parallel-coupled line filters is presented. This method is intended for the suppression of spurious bands which inherently appear in the stopband of this kind of filters. The multispurious suppression is achieved by means of a precise control of the coupling between resonators at unwanted resonant frequencies. The coupling section lengths between successive resonators are used as control parameters to obtain the required couplings. The dependence of the coupling coefficients on coupling section lengths at resonant frequencies is given by closed expressions, obtained following an energetic coupling approach. Several microstrip bandpass filters designed following the new method are presented as examples. These filters feature wide spurious-free bands with high rejection levels.This work has been supported in part by the ‘Centro de Investigación Científica y Tecnològica (CICYT)’ under the Spanish National Project TEC2010-21520-C04-02, and by a research grant from the Generalitat Valenciana

Microwave Planar Resonant Solutions for Glucose Concentration Sensing: A Systematic Review

International audienceThe measurement of glucose concentration finds interesting potential applications in both industry and biomedical contexts. Among the proposed solutions, the use of microwave planar resonant sensors has led to remarkable scientific activity during the last years. These sensors rely on the changes in the dielectric properties of the medium due to variations in the glucose concentration. These devices show electrical responses dependent on the surrounding dielectric properties, and therefore the changes in their response can be related to variations in the glucose content. This work shows an up-to-date review of this sensing approach after more than one decade of research and development. The attempts involved are sorted by the sensing parameter, and the computation of a common relative sensitivity to glucose is proposed as general comparison tool. The manuscript also discusses the key points of each sensor category and the possible future lines and challenges of the sensing approach