Substrate Integrated Coaxial Filters with Fixed and Tunable Responses

Wireless and mobile communications are already playing an important role in our lives, and this will can only grow more and more due to the predominant importance and use of modern smartphones, tablets and any kind of connected devices. With this is mind, the spectrum for wireless and mobile communications is becoming incredibly overcrowded, leading to increasing requirements for RF front-end filters. This progress has encouraged an impressive need for developing low-cost, high performance, mass-producible, small footprint, and highly integrated front-end solutions for microwave and millimeter-wave systems and applications including emerging 5G and future wireless platforms. In this context, high quality factor resonators are usually typical basic building blocks of many high performance passive and active circuits, and its design has become even more challenging in the last decade. As a result, Substrate Integrated Waveguide (SIW) technology has attracted scientific community and industry attention as a very good candidate for developing such desired high-Q planar microwave devices. Recently, SIW is demonstrating to be a successful approach for implementing microwave and mm-wave filters with high Q-factor, easy integration with other planar circuits, and for mass-production manufacturing processes in many technologies (i.e. Printed Circuit Board (PCB) and Low Temperature Co-fired Ceramics (LTCC) technologies among them). Its enormous similarity with waveguides is probably one of the main reasons why the development of SIW-based components and circuits is rapidly growing among the research community. Other potential features that, combined with the former advantages, could be of huge interest in a wide range of wireless and mobile applications are a lively set of research subjects, such as compactness, advanced filtering responses, and recently frequency-agility capabilities. These key features have been recently introduced in the design of microwave filters for the next-generation wireless systems. Taking into account the above-mentioned background, the work carried out during the course of this PhD Thesis has been directed towards a further study of SIW technology to propose, analyze and develop an innovative and original resonator topology. The proposed topology is based on the extension of the classical coaxial waveguide resonator to SIW technology, and must take advantage of the characteristics of SIW devices to allow the design of improved and innovative microwave resonator filters for advanced wireless systems. This PhD Thesis includes the latest improvements made on this topic, from the working principles of the basic coaxial SIW block, until different applications for the design of compact quasi-elliptic and reconfigurable microwave filters. The results are promising and demonstrate the validity of the proposed topology for the design of high-Q microwave filters, as well as its potential application to implement complex designs. The general knowledge gained from these cases of study can be considered a good base for further developing this technology, which can help to improve its EM performance, and also contribute to a more general use in the market.Las comunicaciones inalámbricas y móviles juegan un papel importante en nuestras vidas, y esto sólo puede ir a más debido a su enorme importancia y al uso de los modernos teléfonos inteligentes (del inglés, smartphones), tabletas y toda clase de dispositivos inalámbricos. Con todo esto en mente, el espectro electromagnético para comunicaciones inalámbricas y móviles se está saturando cada día más, lo que conlleva un constante aumento de los requisitos para los filtros de radio-frecuencia usados en las cabeceras de dichos sistemas. Este progreso ha llevado a un creciente interés en desarrollar componentes de microondas de bajo coste, alto rendimiento, pequeño tamaño, que permitan implementar soluciones altamente integradas para sistemas de alta frecuencia (i.e. microondas y ondas milimétrica) y sus aplicaciones, incluyendo entre ellas la emergente conexión 5G y las futuras plataformas inalámbricas. En este contexto, los resonadores de elevado factor de calidad constituyen generalmente los bloques básicos para el diseño de muchos circuitos pasivos (entre ellos filtros) y activos de alto rendimiento. Su diseño se ha convertido por tanto en un reto aún mayor en la última década. Como resultado de ello, la tecnología de guía de ondas integradas en substrato (Substrate Integrated Waveguide, SIW) ha atraído la atención de la comunidad científica e industrial, al revelarse como una buena aproximación para el desarrollo de dispositivos planares de microondas con excelentes prestaciones eléctricas, y en particular para la implementación de filtros de microondas y onda milimétrica de bajas pérdidas y elevada integración con circuitos en tecnología planar. Además, su flexibilidad se caracteriza también por su adecuación a diferentes procesos de fabricación y producción en masa, en tecnologías tales como los circuitos impresos (Printed Circuit Board, PCB) o la tecnología de materiales cerámicos multi-capa co-sinterizados a baja temperatura (Low Temperature Co-fired Ceramics, LTCC) entre otras. Su enorme similitud con las ya largamente estudiadas guías de onda es, probablemente, una de las principales razones por las cuales el desarrollo de dicho circuitos está creciendo rápidamente entre la comunidad de investigadores. Cabe mencionar como, además de las anteriores ventajas, otras características de la tecnología SIW que podrían ser de gran interés en una amplia gama de aplicaciones inalámbricas y móviles son la miniaturización, la posibilidad de implementar respuestas avanzadas de filtrado y, recientemente, las capacidades de sintonía en frecuencia de los componentes de microondas. De este modo, el trabajo desarrollado a lo largo de esta Tesis Doctoral se ha orientado hacia el planteamiento, análisis y desarrollo de una topología de resonador innovadora y original. Dicha topología se basa en una extensión de las cavidades coaxiales en guía de onda metálica a una implementación integrada en substrato inspirada en la tecnología SIW. Esta Tesis Doctoral recapitula los últimos avances que se han producido sobre este tema, empezando desde la descripción de los principios fundamentales de funcionamiento de las estructuras, hasta la demostración de varias aplicaciones concretas útiles para el diseño de filtros de microondas muy compactos, con respuestas filtrantes avanzadas y reconfigurables. Los resultados que se van a mostrar a continuación son prometedores, y demuestran la validez de la topología propuesta. El conocimiento general obtenido de los diferentes prototipos fabricados y caracterizados experimentalmente puede considerarse una buena base para seguir desarrollando esta tecnología, lo que puede ayudar a mejorar su rendimiento electromagnético, así como a contribuir a un uso más extendido de estos dispositivos en el mercado.Les comunicacions sense fils i mòbils juguen un paper important en les nostres vides, i això només pot anar a més a causa de la gran importància i l'ús dels moderns telèfons intel·ligents (de l'anglès, smartphones), tablets i tota classe de dispositius sense fil. Tenint en compte tot açò, l'espectre electromagnètic per a comunicacions sense fils i mòbils s'està saturant cada dia més, el que comporta un constant augment dels requisits per als filtres de radiofreqüència usats en les capçaleres d'aquests sistemes. Aquest progrés ha portat a un creixent interès en desenvolupar components de microones de baix cost, alt rendiment, volum reduït, que permeten implementar solucions altament integrades per a sistemes d'alta freqüència (ie. microones i ones mil·limètriques) i les seves aplicacions, incloent l'emergent connexió 5G i les futures plataformes sense fils. En aquest context, els ressonadors d'elevat factor de qualitat constitueixen generalment els blocs bàsics per al disseny de molts circuits passius (entre ells filtres) i actius d'alt rendiment. El seu disseny s'ha convertit per tant en un repte encara més gran en l'última dècada. Com a resultat d'això, la tecnologia de guia d'ones integrades en substrat (Substrate Integrated Waveguide, SIW) ha atret l'atenció de la comunitat científica i industrial, al revelar-se com una bona aproximació per al desenvolupament de dispositius planars de microones amb excel·lents prestacions elèctriques , i en particular per a la implementació de filtres de microones i ones mil·limètriques de baixes pèrdues i elevada integració amb circuits en tecnologia planar. A més, la seua flexibilitat es caracteritza també per la seua adequació a diferents processos de fabricació i producció en massa, en tecnologies com ara els circuits impresos (Printed Circuit Board, PCB) o la tecnologia de materials ceràmics multicapa co-sinteritzats a baixa temperatura (Low Temperature Co-Fired Ceramics, LTCC) entre d'altres. La seua enorme similitud amb les ja llargament estudiades guies d'ona és, probablement, una de les principals raons per les quals el desenvolupament d'aquests circuits està creixent ràpidament entre la comunitat d'investigadors. Cal destacar com, a més de les anteriors avantatges, altres característiques de la tecnologia SIW que podrien ser de gran interès en una àmplia gamma d'aplicacions sense fils i mòbils són la miniaturització, la possibilitat d'implementar respostes avançades de filtrat i, recentment, les capacitats de sintonia en freqüència dels components de microones. Aquestes característiques clau s'han introduït recentment en el disseny de filtres microones per als sistemes sense fils de pròxima generació, convertint-se en objecte prioritari d'estudi per part de la comunitat científica. D'aquesta manera, el treball desenvolupat al llarg d'aquesta tesi doctoral s'ha orientat cap al plantejament, anàlisi i desenvolupament d'una topologia de ressonador innovadora i original. Aquesta topologia es basa en una extensió de les cavitats coaxials en guia d'ona metàl·lica a una implementació integrada a substrat inspirada en la tecnologia SIW. Aquesta tesi doctoral recapitula els últims avanços que s'han produït sobre aquest tema, començant des de la descripció dels principis fonamentals de funcionament de les estructures, fins a la demostració de diverses aplicacions concretes útils per al disseny de filtres i microones molt compactes, amb respostes de filtrat avançades i reconfigurables. Els resultats que es mostraran a continuació són prometedors, i demostren la validesa de la topologia proposada. El coneixement general obtingut dels diferents prototips fabricats i caracteritzats experimentalment es pot considerar com una bona base per seguir desenvolupant aquesta tecnologia, el que pot ajudar a millorar el seu rendiment electromagnètic, així com a contribuir a un ús més estès d'aquests dispositius en el merSirci, S. (2017). Substrate Integrated Coaxial Filters with Fixed and Tunable Responses [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/78838TESI

Design of Miniaturized Substrate Integrated Filters Using Aggressive Space Mapping

[EN] An optimization procedure for the design of miniaturized substrate integrated quasi-lumped filters based on aggressive space mapping techniques is presented in this paper. A gradient-descent approach based on a lossy coarse model is employed. Thus, a 3-pole bandpass filter response centered at 10 GHz is designed, manufactured and measured, showing the validity of the technique even if strong dependencies between the different electrical and physical parameters are present.Martínez Pérez, JD.; Sirci, S.; Boria Esbert, VE. (2019). Design of Miniaturized Substrate Integrated Filters Using Aggressive Space Mapping. IEEE. 1-4. https://doi.org/10.1109/NEMO.2019.8853742S1

A Novel Magnetic Coupling for Miniaturized Bandpass Filters in Embedded Coaxial SIW

[EN] In this paper, embedded coaxial substrate integrated waveguide (CSIW) filters with innovative magnetic couplings are presented and studied. By creating the loading capacitance of a combline topology using inner layers of a low-temperature co-fired ceramic (LTCC) stack-up, it is possible to achieve resonator miniaturization while improving the spurious-free band and providing full-packaged solutions. Moreover, a new magnetic coupling scheme consisting of short-ended stripline probes is proposed and analyzed in detail, both for direct and external couplings. An in-line three-pole filter at L-band is designed, manufactured, and measured proving how the proposed approach can be used for designing wideband bandpass filter (BPF) with extremely compact size. The designed BPF is centered at 1.5 GHz with 10% fractional bandwidth (FBW), while the layout size is just 35 x 9.5 mm(2). The experimental results validate the coaxial SIW technology that allows for, at the same time, easy integration, compact size, flexible design, and enhanced stop-band performance.This research was funded by Ministerio de Economia, Industria y Competitividad, Spanish Government, under Research Project TEC2016-75934-C4-3-R.Sirci, S.; Martínez Pérez, JD.; Boria Esbert, VE. (2019). A Novel Magnetic Coupling for Miniaturized Bandpass Filters in Embedded Coaxial SIW. Applied Sciences. 9(3):1-14. https://doi.org/10.3390/app903039411493Chen, X.-P., & Wu, K. (2014). Substrate Integrated Waveguide Filters: Practical Aspects and Design Considerations. IEEE Microwave Magazine, 15(7), 75-83. doi:10.1109/mmm.2014.2355751Rhodes, J. D. (1969). The Stepped Digital Elliptic Filter. IEEE Transactions on Microwave Theory and Techniques, 17(4), 178-184. doi:10.1109/tmtt.1969.1126929Grigoropoulos, N., Sanz-Izquierdo, B., & Young, P. R. (2005). Substrate integrated folded waveguides (SIFW) and filters. IEEE Microwave and Wireless Components Letters, 15(12), 829-831. doi:10.1109/lmwc.2005.860027Li, L., Wu, Z., Yang, K., Lai, X., & Lei, Z. (2018). A Novel Miniature Single-Layer Eighth-Mode SIW Filter With Improved Out-of-Band Rejection. IEEE Microwave and Wireless Components Letters, 28(5), 407-409. doi:10.1109/lmwc.2018.2813883Martinez, J. D., Sirci, S., Taroncher, M., & Boria, V. E. (2012). Compact CPW-Fed Combline Filter in Substrate Integrated Waveguide Technology. IEEE Microwave and Wireless Components Letters, 22(1), 7-9. doi:10.1109/lmwc.2011.2174215Nassar, S. O., & Meyer, P. (2017). Pedestal substrate integrated waveguide resonators and filters. IET Microwaves, Antennas & Propagation, 11(6), 804-810. doi:10.1049/iet-map.2016.0120Ho, M.-H., Li, J.-C., & Chen, Y.-C. (2018). Miniaturized SIW Cavity Resonator and Its Application in Filter Design. IEEE Microwave and Wireless Components Letters, 28(8), 651-653. doi:10.1109/lmwc.2018.2845101Sirci, S., Sanchez-Soriano, M. A., Martianez, J. D., Boria, V. E., Gentili, F., Bosch, W., & Sorrentino, R. (2015). Design and Multiphysics Analysis of Direct and Cross-Coupled SIW Combline Filters Using Electric and Magnetic Couplings. IEEE Transactions on Microwave Theory and Techniques, 63(12), 4341-4354. doi:10.1109/tmtt.2015.2495287Riblet, H. J. (1983). An Accurate Approximation of the Impedance of a Circular Cylinder Concentric with an External Square Tube. IEEE Transactions on Microwave Theory and Techniques, 31(10), 841-844. doi:10.1109/tmtt.1983.1131615Yang, T., Ho, K., & Rebeiz, G. M. (2014). Compact Self-Shielded 2–3 GHz High-Q Coaxial Fixed and Tunable Filters. IEEE Transactions on Microwave Theory and Techniques, 62(12), 3370-3379. doi:10.1109/tmtt.2014.236481

Low Loss Tunable Filters in Substrate Integrated Waveguide

[EN] In this work, the design and experimental results of compact low-loss filters, based on the extension of the classical coaxial waveguide resonator to Substrate Integrated Waveguide technology, are successfully demonstrated. The design, fabrication and measurement of a continuously tunable cavity resonator and a two-pole filter at S-band in single-layer SIW technology are presented. These structures keep the low-cost fabrication scheme of single-layer PCB processing, while requiring less than half the area compared to a conventional SIW design.The authors would like to thank Generalitat Valenciana and MICINN (Spanish Government) for its financial support under projects GV/2009/007 and TEC2010-21520-C04-01.Sirci, S.; Martínez Pérez, JD.; Taroncher Calduch, M.; Boria Esbert, VE. (2012). Low Loss Tunable Filters in Substrate Integrated Waveguide. Waves. 1(4):69-78. http://hdl.handle.net/10251/57922S69781

Advanced Filtering Solutions in Coaxial SIW Technology Based on Singlets, Cascaded Singlets, and Doublets

(c) 2019 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.[EN] The use of singlets, cascaded singlets and doublets in coaxial substrate integrated waveguide (SIW) technology is proposed in this paper, with the aim of implementing low-loss filters with very compact size and highly-selective symmetric, asymmetric as well as dual-band responses. Singlets based on coaxial SIW resonator structures with source-load coupling are presented and studied. Then, different filter examples based on N cascaded singlets are designed, fabricated and measured at 7.5 GHz, with up to N transmission zeros (TZs) that can be easily located below and above the passband. Moreover, the application of doublets based on a dual-mode coaxial SIW resonator with source-load coupling for achieving extremely compact dual-band filters is presented, and two examples with different bandwidth configuration for each channel are designed, demonstrating the flexibility of the proposed coaxial SIW structure. The obtained experimental results of the different implemented filters show a good agreement with simulations, thus confirming the interesting potential application of these structures for the design of very compact devices with advanced filtering responses.This work was supported by the Ministerio de Economia, Industria y Competitividad, Spanish Government, under Project TEC2016-75934-C4-3-R.Sirci, S.; Sánchez-Soriano, MÁ.; Martínez Pérez, JD.; Boria Esbert, VE. (2019). Advanced Filtering Solutions in Coaxial SIW Technology Based on Singlets, Cascaded Singlets, and Doublets. IEEE Access. 7:29901-29915. https://doi.org/10.1109/ACCESS.2019.2902956S2990129915

Compact Dual-Mode Substrate Integrated Waveguide Coaxial Cavity for Bandpass Filter Design

This letter proposes a new compact filtering building block. It consists of two via holes embedded into a substrate integrated waveguide (SIW) cavity connected to capacitive metal patches at the top layer. This topology provides two coaxial modes performing a doublet filtering configuration. The proposed dual-mode SIW coaxial cavity is studied in detail and guidelines for the filter design are given. As will be shown, the proposed building block presents a high degree of design flexibility, which allows for the design of multiple kind of bandpass filter (BPF) responses, including both narrow- and wide-band BPFs along with transmission zero generation. As a verification, several filters are designed and implemented at 8 GHz.This work has been supported in part by MINECO (Spanish Government) under projects TEC2013-47037-C5-1-R and TEC2013-48036-C3-3-R, and by a “Juan de la Cierva” Research fellowship

Substrate Integrated Waveguide Diplexer Based on Circular Triplet Combline Filters

The design of substrate integrated waveguide (SIW) diplexers, based on combline triplet sections with transmission zeros (TZs) placed below and above the passband, is presented. In order to control the location of the TZs, positive and negative couplings are conveniently provided. A highly compact implementation based on circular substrate integrated coaxial resonators is proposed. An X band diplexer with channel center frequencies at 9.5 and 10.5 GHz and absolute bandwidths of 400 MHz is designed. The structure shows important advantages in terms of size reduction, while keeping good insertion losses as well as high rejection and isolation levels.This work was supported by MINECO (Spanish Government) under projects TEC2103-47037-C5-1-R and TEC2013-48036-C3-3-R.Sirci, S.; Martínez Pérez, JD.; Vague Cardona, JJ.; Boria Esbert, VE. (2015). Substrate Integrated Waveguide Diplexer Based on Circular Triplet Combline Filters. IEEE Microwave and Wireless Components Letters. 25(7):430-432. doi:10.1109/LMWC.2015.2427516S43043225

When Compactness Meets Flexibility: Basic Coaxial SIW Filter Topology for Device Miniaturization, Design Flexibility, Advanced Filtering Responses, and Implementation of Tunable Filters

[EN] Substrate integrated waveguide (SIW) technology [1], [2] is a well established and successful approach for implementing planar microwave filters with very stringent requirements in terms of quality (Q) factor and also with the ability to integrate into a system. Optimized SIW filters can reach a Q factor of 200-800 using low-loss substrates and standard fabrication procedures [3]. Furthermore, packaging and electromagnetic (EM) shielding, power-handling capabilities, and low-cost batch manufacturing are other broadly recognized strengths of this approach. However, SIW filters are still larger than most of their planar counterparts; in addition, advanced topologies are not always easy to accommodate, and filter reconfigurability usually leads to very complex implementation [4]-[6]Martínez Pérez, JD.; Sirci, S.; Boria Esbert, VE.; Sánchez-Soriano, MÁ. (2020). When Compactness Meets Flexibility: Basic Coaxial SIW Filter Topology for Device Miniaturization, Design Flexibility, Advanced Filtering Responses, and Implementation of Tunable Filters. IEEE Microwave Magazine. 21(6):58-78. https://doi.org/10.1109/MMM.2020.2979155S587821

Design and Multiphysics Analysis of Direct and Cross-Coupled SIW Combline Filters Using Electric and Magnetic Couplings

In this paper, combline substrate integrated waveguide (SIW) filters using electric and magnetic couplings are thoroughly studied. Thus, a negative coupling scheme consisting on an open-ended coplanar probe is proposed and analyzed in detail. Several in-line 3-pole filters at C-band are designed, manufactured and measured showing how the presented approach can be used for implementing direct couplings while enabling an important size reduction and improved spurious-free band compared to conventional magnetic irises. A fully-packaged quasi-elliptic 4-pole filter is also designed at 5.75 GHz showing how the negative coupling structure can be used for introducing transmission zeros by means of cross-couplings between non-adjacent resonators. Finally, average and peak power handling capabilities of these filters have been also analyzed from a multiphysics point of view. Measured results validate the theoretical predictions confirming that combline SIW filters can handle significant levels of continuous and peak power, providing at the same time easy integration, compact size and advanced filtering responses.This work was supported in part by MINECO (Spanish Government) under projects TEC2013-47037-C5-1-R and TEC2013-48036-C3-3-R. This paper is an expanded version from the IEEE MTT-S International Microwave Symposium, Phoenix, AZ, USA, May 17-22, 2015.Sirci, S.; Sánchez Soriano, MÁ.; Martínez Pérez, JD.; Boria Esbert, VE.; Gentili, F.; Boesch, W.; Sorrentino, R. (2015). Design and Multiphysics Analysis of Direct and Cross-Coupled SIW Combline Filters Using Electric and Magnetic Couplings. IEEE Transactions on Microwave Theory and Techniques. 63(12):4341-4354. doi:10.1109/TMTT.2015.2495287S43414354631

Compact CPW-fed combline filter in substrate integrated waveguide technology

“© © 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, 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 component of this work in other works.”In this letter, the design and experimental results of compact low loss combline filters, based on the extension of the classical coaxial waveguide resonator to Substrate Integrated Waveguide (SIW) technology, are succesfully demonstrated. A three-pole 5% FBW Chebyshev filter has been designed, fabricated and measured. The fabricated device shows an excellent agreement with simulated results. These structures keep the low-cost fabrication scheme of single-layer PCB processing, while requiring less than half the area compared to a conventional SIW design.Manuscript received September 07, 2011; accepted October 20, 2011. Date of publication December 16, 2011; date of current version January 11, 2012. This work was supported by Generalitat Valenciana and MICINN (Spanish Government) under projects GV/2009/007 and TEC2010-21520-C04-01.Martínez Pérez, JD.; Sirci, S.; Taroncher Calduch, M.; Boria Esbert, VE. (2012). Compact CPW-fed combline filter in substrate integrated waveguide technology. IEEE Microwave and Wireless Components Letters. 22(1):7-9. https://doi.org/10.1109/LMWC.2011.2174215S7922