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[EN] The objective of this paper is to advance the state of the art in the characterization of the multipactor effect in dielectric materials. The materials studied are the most commonly used dielectrics in space applications, namely, Alumina, Rexolite, Rogers RT5870, Rohacell, Teflon, and Ultem 1000. In this paper, a new family of coaxial waveguide components, covering the L- and S-bands, with a wideband, low-pass response has been designed, and six different prototypes have been specifically optimized and manufactured. The six prototypes have then been used to simulate and measure the multipactor breakdown susceptibility charts for the six dielectric materials investigated. Finally, the simulation results are compared with the results of the measurement campaign indicating good agreement., This work was supported in part by the European Space Agency through Research Project "Novel Investigation in Multipactor Effect in Ferrite and Other Dielectrics Used in High Power RF Space Hardware" under Grant AO 1-7551/13/NL/GLC and in part by MINECO (Spanish Government) through Research and Development Project under Grant TEC2016-75934-C4-1-R. This paper is an expanded version from the IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes IMWS-AMP 2017, Pavia, Italy, September 20-22, 2017.

[EN] The objective of this paper is to use electromagnetic-based computer-aided design (CAD) tools to investigate the maximum tuning range of channel filters, typically used in satellite payloads. Both circular and rectangular waveguide technologies are investigated. The results of the investigation show that single-mode rectangular waveguide implementations offer substantially wider tuning range, as opposed to classical dual-mode circular waveguide implementations. In addition to simulations, measurements are also presented indicating very good agreement with theory, thereby fully validating the CAD procedure., This work was supported in part by MINECO (Spanish Government) under Research and Development Project TEC2016-75934-C4-1-R and in part by Research and Development Technicians under Grant PTA2015-10839-I.

[EN] The objective of this paper is to demonstrate how inline combline filters can be designed to implement transmission zeros in the filter transfer function. Following the design procedure described in this paper, up to N-1 transmission zeros can be implemented with a filter of order N. In addition to theory, comparisons between simulated and measured results are also presented. The agreement between simulation and measurements is indeed good, thereby fully validating the new combline filter topology, and the proposed design technique.

[EN] This paper reports on the experimental measurement of power threshold levels for the multipactor effect between samples of ferrite material typically used in the practical implementation of L-and S-band circulators and isolators. For this purposes, a new family of wideband, nonreciprocal rectangular waveguide structures loaded with ferrites has been designed with a full-wave electromagnetic simulation tool. The design also includes the required magnetostatic field biasing circuits. The multipactor breakdown power levels have also been predicted with an accurate electron tracking code using measured values for the secondary electron yield (SEY) coefficient. The measured results agree well with simulations, thereby fully validating the experimental campaign., This work was supported in part by the European Space Agency (ESA) through the Research Project Novel Investigation in Multipactor Effect in Ferrite and Other Dielectrics Used in High Power RF Space Hardware under Contract AO 1-7551/13/NL/GLC, in part by the Ministerio de Economia y Competitividad (Spanish Government) through Research and Development under Project TEC2016-75934-C4-1-R and Project TEC2016-75934-C4-2-R, and in part by the European Regional Development Fund under Project TEC2014-55463-C3-3-P.

The objective of this paper is to study multipactor breakdown in coaxial to microstrip transitions. This kind of transitions generally exhibit a gap just below the central pin of the coaxial connector. This gap can create a region where the electric fields are relatively strong so that an electron path may be created that could potentially lead to a multipactor breakdown. In this paper, we study the multipactor modes which may be induced as a function of structural parameters, such as the substrate thickness and the gap length. In particular, it is found that two kinds of electron trajectory can be created leading to critical power levels that are even lower than those obtained with the parallel-plate model, generally used as a conservative model. In this context, we demonstrate that multipactor breakdown can happen for input power levels lower than 500 W. This, in turn, may become a critical issue for the use of classic coaxial to microstrip transitions in new high power satellites whenever payloads are manufactured using planar technology. This work has been supported by the “Agencia Estatal de Investigación (AEI)” and by the EU through the ”Fondo Europeo de Desarrollo Regional -FEDER- Una manera de hacer Europa (AEI/FEDER, UE)”, under the coordinated research project TEC2016-75934-C4, and by the University of Alicante under the research project GRE16-17.

The objective of this paper is to describe how a simple modification in the structure of rectangular waveguide filters based on stepped impedance resonators can yield a significant improvement in the out-of-band response of the filter. In addition to theory, the measured performance of an eight-pole prototype is also discussed, indicating very good agreement with simulations, thereby fully validating the new filter structure.

We propose in this paper a very efficient implementation of the Aggressive Space Mapping (ASM) technique for designing and tuning microwave filters. To illustrate the advantages introduced by the ASM that we propose, we discuss two ASM strategies using both the same commercial finite-elements software tool as the “High Accuracy” space (HA). The first one is based on the use of a classic circuit model as a “Low Accuracy” model (LA) of the filter structure, while the second one is based on a low accuracy Multimode Equivalent Network (MEN) representation of the filter structure. Our investigation shows that while the Circuit-Based ASM requires a number of iterations to reach convergence, the MEN-Based ASM converges in just one step. A justification for this very remarkable behavior is also provided in terms of perturbation theory. Finally, in addition to simulations, measured results for a four-pole filter are also presented thereby fully validating the results obtained.

One method used for designing RF and microwave impedance matching networks is based on tapered lines. This paper shows a simple method to design smooth tapers that take into account the dispersion of the line and the required design bandwidth simultaneously. The taper is designed through optimization of very few parameters. As a result, the reflection coefficient of the taper can be optimally adapted to a given specific mask using the prescribed value of physical length. Experimental results are included for validation of the proposed design method.

This paper introduces a new design methododology for multiband waveguide filters based on a manifold approach. The new design algorithm is based on a subtle modification of the well-known multiplexer design algorithm. Transmission zeros, enhancing the overall performance, are also shown to be naturally produced. In addition to theory, the measured performance of a multiband filter is shown indicating very good agreement with the simulated response, thereby fully validating the new design methodology.

The objective of this paper is to use EM-Based CAD tools to investigate the maximum tunability range of classic dual mode filters in circular waveguide. In addition to simulations, measurements are also presented indicating very good agreement with theory, thereby fully validating the results obtained.

The main goal of this work is the review of the recent advances in the study of the multipactor RF breakdown phenomenon in RF satellite microwave passive devices for space telecommunication applications developed in the Val Space Consortium. In this work several topics related with the multipactor phenomenon will be discussed.