Highly Reliable and Repeatable Soldering Technique for Assembling Empty Substrate Integrated Waveguide Devices

[EN] In this paper, a novel mymargin soldering technique that improves the fabrication process of empty substrate integrated waveguide (ESIW) devices is presented. Up until now, in order to fabricate an ESIW device, the tin solder paste was distributed, before assembling, on the contact surface between layers, in order to ensure a good electrical contact. This process has a low degree of repeatability (random soldering thickness and distribution of tin) and reliability (a significant number of nonworking prototypes due to tin overflow). In this paper, we propose the mechanization of a set of plated vias just next to the metalized walls of the ESIW in the central layer. Next, in the top and bottom covers that close this ESIW, additional plated vias are drilled in the same position so that, when the device is assembled (using screws or rivets), metalized holes can be seen passing through the whole structure from top to bottom. These holes are then used as soldering vias that can guide the tin paste straight to the point where it is needed. When the paste is dried, soldered vias ensure a very good electrical contact between layers. In addition, the fluid tin fills any small gap that appears between layers, thus providing a very good electrical contact and mechanical union. This novel soldering technique has been validated with experimental results. Several prototypes of filters centered at 13 and 35 GHz have been fabricated, proving the repeatability and reliability of the proposed soldering technique.This work was supported by the Ministerio de Economiy Competitividad, Spanish Government, under Project TEC2016-75934-C4-3-R and Project TEC2016-75934-C4-1-R.Martinez, JA.; Belenguer, A.; Esteban González, H. (2019). Highly Reliable and Repeatable Soldering Technique for Assembling Empty Substrate Integrated Waveguide Devices. IEEE Transactions on Components, Packaging and Manufacturing Technology (Online). 9(11):2276-2281. https://doi.org/10.1109/TCPMT.2019.2915688S2276228191

Efficient analysis of metal and dielectric rods in rectangular waveguide with ferrite magnetized transversely

This is an Author's Accepted Manuscript of an article published in Zahra Bahrami, Asghar Keshtkar, Ayaz Ghorbani & Hector Esteban (2020) Efficient analysis of metal and dielectric rods in rectangular waveguide with ferrite magnetized transversely, Journal of Electromagnetic Waves and Applications, 34:2, 141-153 [copyright Taylor & Francis], available online at: http://www.tandfonline.com/10.1080/09205071.2019.1690589[EN] This paper presents a new analytical method based on mode matching technique for a waveguide full of anisotropic material with rods. It is proved that mode matching technique is applicable for the waveguide with anisotropic materials. The problem is considered as a 2D electromagnetic problem assuming no field variation normal to the waveguide length. Incident and scattered fields from circular cylinder rods in ferrite medium are expanded with cylindrical modes, and the fields in the waveguide ports are expanded using progressive and regressive modal summations. In both regions, extraordinary wave number is considered for the fields. Finally, the hybrid mode matching between guided and cylindrical modes is done by projecting continuity equations in the circular boundary containing the rod. The fast Fourier transform is used to solve the matching in the presented method. It is shown, that the new method runs faster than commercial software packages, with very good accuracy.Bahrami, Z.; Keshtkar, A.; Ghorbani, A.; Esteban González, H. (2020). Efficient analysis of metal and dielectric rods in rectangular waveguide with ferrite magnetized transversely. Journal of Electromagnetic Waves and Applications. 34(2):141-153. https://doi.org/10.1080/09205071.2019.1690589S141153342Bachiller, C., Gonzalez, H. E., Boria Esbert, V. E., Belenguer Martinez, A., & Morro, J. V. (2007). Efficient Technique for the Cascade Connection of Multiple Two-Port Scattering Matrices. IEEE Transactions on Microwave Theory and Techniques, 55(9), 1880-1886. doi:10.1109/tmtt.2007.904076Koshiba, M., & Suzuki, M. (1986). Finite-Element Analysis of H-Plane Waveguide Junction with Arbitrarily Shaped Ferrite Post. IEEE Transactions on Microwave Theory and Techniques, 34(1), 103-109. doi:10.1109/tmtt.1986.1133286Ise, K., & Koshiba, M. (1989). Equivalent circuits for dielectric posts in a rectangular waveguide. IEEE Transactions on Microwave Theory and Techniques, 37(11), 1823-1825. doi:10.1109/22.41054Ise, K., & Koshiba, M. (1990). Dielectric post resonances in a rectangular waveguide. IEE Proceedings H Microwaves, Antennas and Propagation, 137(1), 61. doi:10.1049/ip-h-2.1990.0011Auda, H. A., & Smith, C. E. (1990). The resonance method for evaluating the impedances of the equivalent network for dielectric posts in a rectangular waveguide. IEEE Transactions on Microwave Theory and Techniques, 38(11), 1595-1602. doi:10.1109/22.60004Diaz Caballero, E., Esteban, H., Belenguer, A., & Boria, V. (2012). Efficient Analysis of Substrate Integrated Waveguide Devices Using Hybrid Mode Matching Between Cylindrical and Guided Modes. IEEE Transactions on Microwave Theory and Techniques, 60(2), 232-243. doi:10.1109/tmtt.2011.2178424Nafe, A., & Shamim, A. (2015). An Integrable SIW Phase Shifter in a Partially Magnetized Ferrite LTCC Package. IEEE Transactions on Microwave Theory and Techniques, 63(7), 2264-2274. doi:10.1109/tmtt.2015.2436921Ghaffar, F. A., & Shamim, A. (2015). A Partially Magnetized Ferrite LTCC-Based SIW Phase Shifter for Phased Array Applications. IEEE Transactions on Magnetics, 51(6), 1-8. doi:10.1109/tmag.2015.2404303Ghiotto, A., Adhikari, S., & Wu, K. (2012). Ferrite-Loaded Substrate Integrated Waveguide Switch. IEEE Microwave and Wireless Components Letters, 22(3), 120-122. doi:10.1109/lmwc.2012.218385

Novel empty substrate integrated waveguide for high performance microwave integrated circuits

"(c) 20xx 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."Abstract Over the last years, a great number of substrate integrated circuits has been developed. These new circuits are a compromise between the advantages of classical waveguide technologies, such as high quality factor and low losses, and the advantages of planar circuits, such as low cost and easy compact integration. Although their quality factor and losses are better than for planar circuits, these characteristics are worse than in the case of waveguides, mainly due to the presence of the dielectric substrate. In order to improve the performance of the integrated circuits, a new methodology for manufacturing empty waveguides, without a dielectric substrate, but at the same time completely integrated in a planar substrate, is proposed in this work. A wideband transition with return losses greater than 20 dB in the whole bandwith of the waveguide allows the integration of the empty waveguide into the planar substrate so that the waveguide can be directly accessed with a microstrip line. Therefore, a microwave circuit integrated in a planar substrate, but at the same time with a very high quality factor (measured quality factor is 4.5 times higher than for the same filter in the substrate integrated waveguide), and very low losses is successfully achieved.This work was supported by the Ministerio de Ciencia e Innovacion, Spanish Goverment, under Research Project TEC2010-21520-C04-03 and Research Project EC2010-21520-C04-01, and by the Autonomous Government of Castilla-La Mancha under Research Project PPII10-0047-0220.Belenguer Martínez, Á.; Esteban González, H.; Boria Esbert, VE. (2014). Novel empty substrate integrated waveguide for high performance microwave integrated circuits. IEEE Transactions on Microwave Theory and Techniques. 62(4):832-839. https://doi.org/10.1109/TMTT.2014.2309637S83283962

Asymptotic zero distribution for a class of extremal polynomials

We consider extremal polynomials with respect to a Sobolev-type p-norm, with 1and measures supported on compact subsets of the real line. For a wide class of such extremal polynomials with respect to mutually singular measures (i.e. supported on disjoint subsets of the real line), it is proved that their critical points are simple and contained in the interior of the convex hull of the support of the measures involved and the asymptotic critical point distribution is studied. We also find the nth root asymptotic behavior of the corresponding sequence of Sobolev extremal polynomials and their derivatives.A.D.G. was supported by the Research Fellowship Program, Ministerio de Economía, Industria y Competitividad of Spain, under grant BES-2016-076613. The authors G.L.L. and H.P.C. were supported by the Ministerio de Economía, Industria y Competitividad of Spain, under grant MTM2015-65888-C4-2-P

Fast Frequency Sweep Technique Based on Segmentation for the Acceleration of the Electromagnetic Analysis of Microwave Devices

[EN] The characterization of communication devices in a certain frequency band can be accelerated if a fast frequency sweep technique is used instead of a discrete frequency sweep. Existing fast frequency sweep techniques are either complex or specific for a certain electromagnetic solver. In this work, a new fast frequency sweep method is proposed that consists in segmenting the device under analysis into simple building blocks. Each building block is characterized with a generalized (multimode) circuital matrix whose elements present a simple and flat frequency response that is interpolated using natural cubic splines with very few points. In this way, the response of each block along the whole frequency band is obtained efficiently and accurately with as many frequency points as desired. Then, the circuital matrices of all the blocks are cascaded and the circuital matrix of the whole device in obtained. The new fast frequency sweep was successfully applied to the analysis of different types of devices (all metallic rectangular waveguide filter, dielectric loaded rectangular waveguide filter, and substrate integrated waveguide filter). The computational times were reduced to 15% or 19%, depending on the device, when compared with a discrete frequency sweep using the same electromagnetic solver.This research was funded by Ministerio de Economia, Industria y Competitividad, Spanish Government, under Research Projects TEC2016-75934-C4-3-R and TEC2016-75934-C4-1-R.Martínez-Zamora, JÁ.; Belenguer Martínez, A.; Esteban González, H. (2019). Fast Frequency Sweep Technique Based on Segmentation for the Acceleration of the Electromagnetic Analysis of Microwave Devices. Applied Sciences. 9(6):1-16. https://doi.org/10.3390/app9061118S11696Erdemli, Y. E., Reddy, C. J., & Volakis, J. L. (1999). Awe Technique in Frequency Domain Electromagnetics. Journal of Electromagnetic Waves and Applications, 13(3), 359-378. doi:10.1163/156939399x00961Reddy, C. J., Deshpande, M. D., Cockrell, C. R., & Beck, F. B. (1998). Fast RCS computation over a frequency band using method of moments in conjunction with asymptotic waveform evaluation technique. IEEE Transactions on Antennas and Propagation, 46(8), 1229-1233. doi:10.1109/8.718579Polstyanko, S. V., Dyezij-Edlinger, R., & Jin-Fa Lee. (1997). Fast frequency sweep technique for the efficient analysis of dielectric waveguides. IEEE Transactions on Microwave Theory and Techniques, 45(7), 1118-1126. doi:10.1109/22.598450Chiprout, E., & Nakhla, M. S. (1995). Analysis of interconnect networks using complex frequency hopping (CFH). IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, 14(2), 186-200. doi:10.1109/43.370425Gustavsen, B., & Semlyen, A. (1999). Rational approximation of frequency domain responses by vector fitting. IEEE Transactions on Power Delivery, 14(3), 1052-1061. doi:10.1109/61.772353Bandler, J. W., Biernacki, R. M., Shao Hua Chen, & Ya Fei Huang. (1997). Design optimization of interdigital filters using aggressive space mapping and decomposition. IEEE Transactions on Microwave Theory and Techniques, 45(5), 761-769. doi:10.1109/22.575598Ros, J. V. M., Pacheco, P. S., Gonzalez, H. E., Esbert, V. E. B., Martin, C. B., Calduch, M. T., … Martinez, B. G. (2005). Fast automated design of waveguide filters using aggressive space mapping with a new segmentation strategy and a hybrid optimization algorithm. IEEE Transactions on Microwave Theory and Techniques, 53(4), 1130-1142. doi:10.1109/tmtt.2005.845685Alos, J. T., & Guglielmi, M. (1997). Simple and effective EM-based optimization procedure for microwave filters. IEEE Transactions on Microwave Theory and Techniques, 45(5), 856-858. doi:10.1109/22.575610Bachiller, C., Gonzalez, H. E., Boria Esbert, V. E., Belenguer Martinez, A., & Morro, J. V. (2007). Efficient Technique for the Cascade Connection of Multiple Two-Port Scattering Matrices. IEEE Transactions on Microwave Theory and Techniques, 55(9), 1880-1886. doi:10.1109/tmtt.2007.904076Interpolación de Splineshttps://www.uv.es/diaz/mn/node40.htmlBachiller, C., Esteban, H., Mata, H., Valdes, M. Á., Boria, V. E., Belenguer, Á., & Morro, J. V. (2010). Hybrid Mode Matching Method for the Efficient Analysis of Metal and Dielectric Rods in H Plane Rectangular Waveguide Devices. IEEE Transactions on Microwave Theory and Techniques. doi:10.1109/tmtt.2010.208395

Determining factors of education job match in socio-educational degrees

[ES] Actualmente, el gran crecimiento de la oferta universitaria está produciendo un superávit de demandantes de empleo cualificados que no pueden ser absorbidos por el mercado de trabajo. Esto provoca situaciones de desajuste laboral. El presente estudio tiene como objetivo describir los factores asociados al desajuste formación-empleo en los titulados en el ámbito socioeducativo, concretamente en los grados de Trabajo Social, Educación Primaria, Educación Infantil y Educación Social. Se utilizó una amplia muestra de datos a nivel nacional. Los resultados indican que las variables educativas, entre ellas la finalización de otros estudios universitarios, son especialmente determinantes en la predicción de los desajustes. Los desajustes se encuentran, además, vinculados a aquellos trabajadores con jornadas laborales parciales.[EN] Currently, the large growth in university supply is producing a surplus of qualified job seekers who cannot be absorbed by the labour market. This leads to situations of labour mismatch. The aim of this study is to describe the factors associated with the training-employment mismatch in graduates in the socio-educational field, specifically in the degrees of Social Work, Primary Education, Early Childhood Education and Social Education. A large sample of national data was used. The results indicate that educational variables, including completion of other university studies, are particularly important in predicting mismatches. The mismatches are also found to be linked to those workers with part-time work

Polynomials of least deviation from zero in Sobolev p-Norm

The first part of this paper complements previous results on characterization of polynomials of least deviation from zero in Sobolev p-norm (1<p<∞) for the case p=1. Some relevant examples are indicated. The second part deals with the location of zeros of polynomials of least deviation in discrete Sobolev p-norm. The asymptotic distribution of zeros is established on general conditions. Under some order restriction in the discrete part, we prove that the n-th polynomial of least deviation has at least n−d∗ zeros on the convex hull of the support of the measure, where d∗ denotes the number of terms in the discrete part.The research of H. Pijeira-Cabrera was partially supported by Ministry of Science, Innovation and Universities of Spain, under grant PGC2018-096504-B-C33. Funding Open Access funding provided by Universidad Carlos III de Madrid thanks to the CRUE-CSIC 2021 agreement with Springer Nature

Sincronicidad de ciclos económicos en América Latina: motivacion para su estudio y sumario de Metodologías aplicadas

Sincronicidad de ciclos económicos en América Latina: motivacion para su estudio y sumario de Metodologías aplicada

High-Performance Coplanar Waveguide to Empty Substrate Integrated Coaxial Line Transition

Recently, a new empty coaxial structure, entirely built with printed circuit boards, has been proposed. The resulting coaxial line has low radiation, low losses, high-quality factor, and is nondispersive. Up to now, this coaxial line has not been completely integrated in a planar substrate, since a working transition to a traditional planar line has not been defined yet. Therefore, in this paper, a high-quality transition from coplanar waveguide to this new empty coaxial line is proposed. With this transition, the coaxial line is completely integrated in a planar circuit board, so that it truly becomes an empty substrate-integrated coaxial line. The proposed transition has been fabricated. Both full-wave simulated and measured results show an excellent agreement. Therefore, the proposed transition is suitable to develop completely substrate-integrated components for applications in wideband communication systems that require very high quality responses and protection from external interferences. To show this fact, this new transition has been applied to integrate a high-performance empty coaxial filter in a planar substrate. The measured response of this filter is excellent, and proves the goodness of the proposed transition that has enabled, for the first time, the complete integration of an empty coaxial line in a planar substrate.This work was supported by the Ministerio de Economia y Competitividad, Spanish Goverment under Research Projects TEC2013-47037-C5-3-R and TEC2013-47037-C5-1-R.Belenguer Martínez, Á.; Borja, A.; Esteban González, H.; Boria Esbert, VE. (2015). High-Performance Coplanar Waveguide to Empty Substrate Integrated Coaxial Line Transition. IEEE Transactions on Microwave Theory and Techniques. 63(12):4027-4034. doi:10.1109/TMTT.2015.2496271S40274034631

Cross-guide Moreno directional coupler in empty substrate integrated waveguide

[EN] Substrate integrated waveguides (SIWs) combine the advantages of rectangular waveguides (low losses) and planar circuits (low cost and low profile). Empty substrate integrated waveguide (ESIW) has been proposed as a novel configuration in SIWs recently. This technology significantly reduces the losses of conventional SIW by removing its inner dielectric. The cross-guide directional coupler is a well-known low-profile design for having a broadband waveguide coupler. In this paper a cross-guide coupler with ESIW technique is proposed. In such a manner, the device can be integrated with microwave circuits and other printed circuit board components. It is the first time that a cross-guide coupler is implemented in ESIW technology. The designed, fabricated, and measured device presents good results as a matter of insertion loss of 1 dB (including transitions), reflection under 20 dB, coupling between 19.5 and 21.5 dB, and directivity higher than 15 dB over targeted frequency range from 12.4 GHz to 18 GHz. The coupler implemented in ESIW improves the directivity when compared to similar solutions in other empty substrate integrated waveguide solutions.This work was supported by the Ministerio de Economia y Competitividad, Spanish Goverment, under research projects TEC2013-47037-C5-3-R and TEC2013-47037-C5-1-R. All the data related with this work can be requested from H. Esteban ([email protected]).Miralles-Navarro, E.; Belenguer, Á.; Esteban González, H.; Boria Esbert, VE. (2017). Cross-guide Moreno directional coupler in empty substrate integrated waveguide. Radio Science. 52(5):597-603. https://doi.org/10.1002/2017RS006244S597603525Ball, J. A. R., & Sulda, T. M. (2000). Small aperture crossed waveguide broad wall directional couplers. IEE Proceedings - Microwaves, Antennas and Propagation, 147(4), 249. doi:10.1049/ip-map:20000570Belenguer, A., Esteban, H., & Boria, V. E. (2014). Novel Empty Substrate Integrated Waveguide for High-Performance Microwave Integrated Circuits. IEEE Transactions on Microwave Theory and Techniques, 62(4), 832-839. doi:10.1109/tmtt.2014.2309637Chen , J. 1998 Cross-guide coupler modeling and design TDA Prog. Tech. Rep. Jet Propulsion Lab., California Inst. of Technol. Pasadena, CalifXiao-Ping Chen, Ke Wu, & Drolet, D. (2009). Substrate Integrated Waveguide Filter With Improved Stopband Performance for Satellite Ground Terminal. IEEE Transactions on Microwave Theory and Techniques, 57(3), 674-683. doi:10.1109/tmtt.2009.2013316Cheng, Y. J., & Fan, Y. (2012). Compact substrate-integrated waveguide bandpass rat-race coupler and its microwave applications. IET Microwaves, Antennas & Propagation, 6(9), 1000. doi:10.1049/iet-map.2012.0011Dong, Y., & Itoh, T. (2011). Composite Right/Left-Handed Substrate Integrated Waveguide and Half Mode Substrate Integrated Waveguide Leaky-Wave Structures. IEEE Transactions on Antennas and Propagation, 59(3), 767-775. doi:10.1109/tap.2010.2103025Farzami, F., Forooraghi, K., & Norooziarab, M. (2011). Design and Modeling of a Miniaturized Substrate Integrated Waveguide Using Embedded SRRs. IEEE Antennas and Wireless Propagation Letters, 10, 713-716. doi:10.1109/lawp.2011.2161860Farzami, F., & Norooziarab, M. (2013). Experimental Realization of Tunable Transmission Lines Based on Single-Layer SIWs Loaded by Embedded SRRs. IEEE Transactions on Microwave Theory and Techniques, 61(8), 2848-2857. doi:10.1109/tmtt.2013.2271759Fernandez, M. D., Ballesteros, J. A., & Belenguer, A. (2015). Design of a Hybrid Directional Coupler in Empty Substrate Integrated Waveguide (ESIW). IEEE Microwave and Wireless Components Letters, 25(12), 796-798. doi:10.1109/lmwc.2015.2496803Moreno , A. 1946 A new directional coupler for waveguide Sperry Gyroscope Eng. Rep., Sperry Gyroscope Co. BrooklynRambabu, K., Thiart, H. A., & Bornemann, J. (2005). Simplified analysis for the initial design of rectangular waveguide cross-slot couplers. IEE Proceedings - Microwaves, Antennas and Propagation, 152(4), 226. doi:10.1049/ip-map:20045056Rautschke, F., Maassen, D., Konc, O., & Boeck, G. (2016). Comparison of conventional and substrate integrated waveguide filters for satellite communication. 2016 IEEE MTT-S International Wireless Symposium (IWS). doi:10.1109/ieee-iws.2016.7585467Zhang, Y., Wang, Q., & Ding, J. (2013). A Cross-Guide Waveguide Directional Coupler With High Directivity and Broad Bandwidth. IEEE Microwave and Wireless Components Letters, 23(11), 581-583. doi:10.1109/lmwc.2013.228140