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

Microwave Filters in Planar and Hybrid Technologies with Advanced Responses

[ES] La presente tesis doctoral tiene como principal objetivo el estudio, diseño, desarrollo y fabricación de nuevos dispositivos pasivos de microondas, tales como filtros y multiplexores con respuestas avanzadas para aplicaciones de alto valor añadido (i.e. comerciales, militares, espacio); orientados a distintos servicios, actuales y futuros, en sistemas inalámbricos de comunicación. Además, esta investigación se centrará en el desarrollo de filtros encapsulados de montaje superficial y con un elevado grado de miniaturización. Para ello, se propone investigar distintas técnicas que consigan respuestas muy selectivas o con unas características exigentes en rechazo (mediante la flexible introducción de ceros de transmisión), así como una excelente planaridad en banda (aplicando técnicas tales como la mejora del Q o el diseño de filtros con pérdidas, lossy filters), obteniendo de este modo respuestas mejoradas, con respecto a soluciones conocidas, en los componentes de microondas desarrollados. De forma general, la metodología seguida se iniciará con una búsqueda y conocimiento del estado del arte sobre cada uno de los temas que se acometerán en esta tesis. Tras ello, se establecerá un procedimiento de síntesis que permitirá acometer de forma teórica los objetivos y especificaciones a conseguir en cada caso. Con ello, se establecerán las bases para iniciar el proceso de diseño, incluyendo co-simulación circuital/electromagnética y optimización que permitirán, en última instancia, implementar la solución planteada en cada caso de aplicación concreto. Finalmente, la demostración y validez de todas las investigaciones realizadas se llevará a cabo mediante la fabricación y caracterización experimental de distintos prototipos.[CA] La present tesi doctoral té com a principal objectiu l'estudi, disseny, desenvolupament I fabricació de nous dispositius passius de microones, com ara filtres i multiplexors amb respostes avançades per a aplicacions d'alt valor afegit, (comercials, militars, espai); orientats a oferir diferents serveis, actuals i futurs, en els diferents sistemes sense fils de comunicació. A més, aquesta investigació es centrarà en el desenvolupament de filtres encapsulats de muntatge superficial i amb un elevat grau de miniaturització. Per a això, es proposa investigar diferents tècniques que aconsegueixin respostes molt selectives o amb unes característiques exigents en rebuig (mitjançant la flexible introducció de zeros de transmissió), així com una excel·lent planaritat en banda (aplicant tècniques com ara la millora de l'Q o el disseny de filtres amb perdues, lossy filters), obtenint d'aquesta manera respostes millorades, respecte solucions conegudes, en els components de micrones desenvolupats. De forma general, la metodologia seguida s'iniciarà amb una recerca i coneixement de l'estat de l'art sobre cadascun dels temes que s'escometran en aquesta tesi. Després d'això, s'establirà un procediment de síntesi que permetrà escometre de forma teòrica els objectiusi especificacions a aconseguir en cada cas. Amb això, s'establiran les bases per iniciar el procés de disseny, amb co-simulació circuital / electromagnètica i optimització que permetran, en última instància, implementar la solució plantejada en cada cas d'aplicació concret. Finalment, la demostració i validesa de totes les investigacions realitzades es durà a terme mitjançant la fabricació i caracterització experimental de diferents prototips.[EN] The main objective of this doctoral thesis is the study, design, development and manufacture of new passive microwave components, such as filters and multiplexers with advanced responses for commercials, military and space applications; oriented to other different services, in current and future wireless communication systems. In addition, this research will focus on the development of surface-mounted encapsulated filters with a high degree of miniaturization. With this purpose, it is proposed to investigate different techniques that achieve highly selective responses or with demanding characteristics in rejection (through the flexible introduction of transmission zeros), as well as an excellent in-band planarity (applying techniques such as the Q enhancement or lossy filters), thus obtaining improved responses, with respect to known solutions, in the developed microwave components. In general, the followed methodology will begin with a search and knowledge of the state of the art on each of the topics addressed in this thesis. After that, a synthesis procedure will be established, which will allow the achievement of the objectives and specifications in a theoretical way, for each case. With this, the bases will be established to start the design process, with circuital and electromagnetic co-simulations and optimizations that will allow, ultimately, to implement the proposed solution, in every application case, specifically. Finally, the demonstration and validity of all the investigations will be carried out through the manufacture and experimental characterization of different prototypes.Marín Martínez, S. (2022). Microwave Filters in Planar and Hybrid Technologies with Advanced Responses [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/18894

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

Resistorless Implementation of Lossy Filters Using Coaxial SIW Resonators With Non-uniform Q

[EN] A technique for designing bandpass filters with very flat amplitude response is presented in this paper. The approach is based on the use of non-uniform-Q resonators implemented in coaxial substrate integrated waveguide (SIW) technology. An important unloaded Q-factor ratio can be obtained by adequately controlling several layout parameters of the basic resonator cell, thus enabling to optimize the in-band response of the filter. The approach is experimentally demonstrated at X-band frequencies by designing two resonators in Rogers RO4003C (¿ r = 3.55, tan ¿ = 0.0027) with unloaded Q-factors going from 53 to 270. Then, a 4th-order filter example with 2 transmission zeros is designed, fabricated and measured based on the former results. The filter is centered at 10 GHz with a 280 MHz bandwidth showing a in-band flatness better than 1 dB-pp, which would require an unloaded Q-factor about 600 for a uniform-Q implementation, therefore showing the advantages of the proposed approach for implementing bandpass filters for high-end RF and microwave applications.Marín-Martínez, S.; Martínez Pérez, JD.; Boria Esbert, VE. (2021). Resistorless Implementation of Lossy Filters Using Coaxial SIW Resonators With Non-uniform Q. IEEE. 27-29. https://doi.org/10.1109/IMFW49589.2021.9642374272

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

Miniaturized Ultra-Wideband Bandpass Filter Based on Substrate Integrated Quasi-Lumped Resonators

[EN] A compact ultra-wideband bandpass filter employing substrate integrated quasi-lumped resonators is presented in this paper. A multi-layer hybrid structure is proposed, combining quasi-lumped resonators and surface mount components. This allows a huge miniaturization degree due to the high capacitive loading. Moreover, strong magnetic and electric couplings can be implemented thus enabling the introduction of transmission zeros for improving response selectivity. A filter example centered at 5.35 GHz with a prescribed channel bandwidth of 2.9 GHz has been designed, manufactured and measured. The filter size is smaller than 7×7 mm2. The obtained results show the feasibility of the proposed approach.This project has received funding from the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 811232, the European Space Agency (ESA) under contract 4000124983, and the Ministerio de Ciencia e Innovación (Spanish Government) under project PID2019-103982R-C41Messaoudi, EM.; Martínez Pérez, JD.; Boria Esbert, VE. (2021). Miniaturized Ultra-Wideband Bandpass Filter Based on Substrate Integrated Quasi-Lumped Resonators. IEEE. 201-203. https://doi.org/10.1109/IMFW49589.2021.964238220120

Diseño, Simulación y Construcción de Antenas de Ranuras en Banda Ku con Tecnología SIW

[ES] Utilizando la tecnología SIW (Substrate Integrated Waveguide), se presenta en este trabajo el diseño, simulación y construcción de dos agrupaciones de antenas de ranuras que operan en la banda Ku a la frecuencia de 17GHz. En primer lugar se analiza una agrupación de 2x10 antenas de ranuras; la alimentación llega a la antena por medio de un divisor de potencia de -3dB tipo Y excitado por línea microstrip con un taper diseñado y optimizado para conseguir un buen acoplamiento entre la línea y la guía SIW. La segunda antena es una agrupación de 8x10; donde una red formada por codos y divisores tipo Y proporcionan a la antena una alimentación uniforme en magnitud y fase con un parámetro S11 menor de -20dB en la banda de interés. En la tercera antena se utiliza la estructura de la agrupación de 8x10 mejorando su tamaño al tener la red de alimentación en otra capa detrás de la antena. Para conseguir el acoplo entre las capas (antena y red) se utilizan transiciones entre guías SIW (acoplo por ranura) cuyos resultados experimentales también son presentados.[EN] Using SIW technology (Substrate Integrated Waveguide), this work presents design, simulation and construction of two slot array antennas operating in Ku band at 17GHz. First, a two-by-ten slot array antenna is presented; the feeding is formed by Y type power divider of -3dB. To excite SIW guide, microstrip line with taper is designed and optimized to get good matching between line and SIW guide. The second antenna is an eight-by-ten slot array; where the feeding network is formed by bends and Y type dividers providing uniform feeding in magnitude and phase. The S11 parameter is smaller than -20dB in the whole frequency bandwidth. Third array use the structure of above antenna (eigth-by-ten) improving its size. Feeding network is located at the bottom of the antenna. To connect the layers a transition between two SIW by means of a coupling slot has been designed and also experimental results are presented.Navarro Méndez, DV. (2010). Diseño, Simulación y Construcción de Antenas de Ranuras en Banda Ku con Tecnología SIW. http://hdl.handle.net/10251/27147.Archivo delegad

Emerging Trends in Techniques and Technology as Applied to Filter Design

In the last decade, the filter community has innovated both design techniques and the technology used for practical implementation. In design, the philosophy has become "if you can't avoid it, use it", a very practical engineering approach. Modes previously deemed spurious are intentionally used to create in-line networks incorporating real or imaginary transmission zeros and also reduce the number of components and thus further miniaturize; spurious responses are re-routed to increase the passband width or stopband width, frequency variation in couplings is used to create complex transfer functions, with all of these developments using what was previously avoided. Clever implementations of baluns into passive and active networks is resulting in a new generation of noise-immune filters for 5G and beyond. Finally, the use of a diakoptic approach to synthesis has appeared an evolving approach in which small blocks ("singlets", "doublets", etc.) are cascaded to implement larger networks, (reducing the need for very complex synthesis), with this new approach promising a large impact on the implementation of practical structures. Filter technology has migrated towards "observe it and then adapt it", pragmatically repurposing tools not specifically originally intended for the applications. Combinations of surface wave and bulk wave resonators with L-C networks are improving the loss characteristics of filters in the region below 2 GHz. Lightweight alloys and other materials designed for spacecraft are being used in filters intended for space, to provide temperature stability without the use of heavy alloys such as Invar. Fully-enclosed waveguide is being replaced in some cases by planar and quasiplanar structures propagating quasi-waveguide modes. This is generically referred to as SIW (Substrate Integrated Waveguide). Active filters trade noise figure for insertion loss but perhaps will offer advantage in terms of size and chip-level implementation. Finally, the era of reconfiguration might be approaching, as the basic networks are evolving, perhaps lacking only the appearance of lower-loss, higher-IP solid-state tuning elements

High Gain Planar Antenna Structures for Ka-band Applications

Antennas are an essential part of a communication system as they control a coverage area of the signal. The millimeter wave band has the potential to offer numerous radio applications which require the large bandwidth channels. Due to the current cellular subscribers’ demand of higher data rates, even cellular communication is expected to move in millimeter wave communications at Ka band of 26.5 GHz to 40 GHz. However, millimeter waves are sensitive to the high degree of atmospheric and oxygen absorption losses. This challenge of the millimeter wave communication can be tackled by employing high gain antennas. In addition, modern electronic products require compact handheld devices to offer the user-friendly system as well as capture the market. Therefore, planar antenna structures are apt for these communication systems. In this thesis, two antenna structures are presented at the Ka band for millimeter wave communications. Initially, four element patch antenna is presented for high gain in the broadside direction. Patch elements are excited using an aperture coupling from 50Ω microstrip line. Air-gap cavity is used to improve the impedance bandwidth of the design. This structure obtains a relatively moderate impedance bandwidth of 4.6%. The proposed four-element patch antenna exhibits a flat gain over an operating band with 13.8 dB gain at the design frequency. The antenna achieves a wide beamwidth of 700 in H plane. In addition, side lobe levels in E and H planes are -14.5 dB and 23 dB respectively. For the second prototype, an Antipodal Fermi-Linear Tapered Slot Antenna (AFLTSA) is presented to achieve the wide impedance bandwidth with high flat gain for endfire radiation. Substrate Integrated waveguide (SIW) technique is utilized to feed the AFLTSA which reduces insertion losses of the structure. Fermi-Dirac distributed curve in conjunction with a linear curve for a tapered slot increases the coupling of the electric field from a substrate integrated waveguide to the tapered slot. Knife edge rectangular corrugation profile is used at edges of AFLTSA in order to reduce the side lobes and cross polarization levels of radiation pattern. The proposed structure achieves the wide impedance bandwidth to support requirements for high data rate channels. Measurement results from a fabricated prototype exhibit a flat gain over an entire operating frequency band with 16.4 dB gain at 28 GHz. The wide impedance bandwidth is achieved with return loss below 15 dB. Proposed structure has low side lobe levels of -13.9 dB in H plane and -19.5 dB in E plane. In addition, it offers a low cross polarization level of -22 dB

Diseño de array de parches 2D alimentado por red corporativa en tecnología mixta de líneas microstrip y SIW

Este documento presenta el diseño, construcción y medida de una antena multicapa de tipo array para funcionamiento en banda Ku de frecuencias y posible aplicación en comunicaciones por satélite y posicionamiento radar. El array consiste en una agrupación de 4 x 4 parches apilados con polarización lineal y alimentados mediante una red de alimentación implementada en dos capas, una en tecnología microstrip y otra en guía de onda sobre sustrato impreso (Substrate Integrated Waveguide, SIW). La simetría de la red de alimentación da lugar a una ley de iluminación de tipo uniforme para todos los elementos radiantes. Asimismo, esta simetría facilita la réplica del array 4 x 4 propuesto en antenas con más elementos y mayor ganancia. La alimentación de la antena se realiza mediante conector coaxial de 50 ohmios. Durante la fase de diseño, se ha realizado un proceso modular, donde cada parte de la antena se ha optimizado por separado y posteriormente integrado, ahorrando así en tiempo de simulación. El primer prototipo diseñado, con un conector coaxial vertical como alimentación principal, presenta un ancho de banda de adaptación mejor que -15 dB del 17% y del 20% para adaptación mejor que -10 dB. La ganancia conseguida en simulación a 17 GHz se sitúa en los 18,4 dBi. Esta antena ha sido construida y medida en la Escuela Politécnica Superior de la Universidad Autónoma de Madrid, obteniéndose una respuesta en adaptación muy deteriorada. Se ha detectado la gran sensibilidad de la antena a la transición vertical de entrada, por lo que se ha propuesto un nuevo diseño con transición horizontal. Esta transición ha probado ser mucho más estable en trabajos previos. El nuevo prototipo se ha construido, logrando medir un ancho de banda a -10 dB de más del 15,8%. La ganancia medida a 17 GHz cae a 16,7 dBi debido a limitaciones de fabricación.In this article, the design, manufacture and measurement of a multilayer antenna array at Ku band to be used in satellite communications and radar positioning is presented. The antenna consists on a 4 x 4 linearly polarized stacked-patch array fed by a double-layer feeding network implemented in both microstrip and Substrate Integrated Waveguide (SIW) technologies. Due to the symmetry of the feeding network, the radiating elements are uniformly excited. In addition, the replication of the proposed 4 x 4 array into larger high-gain antennas is straightforward thanks to the symmetry of the structure. A 50-ohm coaxial connector is the main feeding source of the antenna. A modular design process has been carried out, separately optimizing each antenna element before the final integration, therefore saving simulation time. The first prototype is fed by a vertical coaxial connector, and the simulated -15 dB matching bandwidth is 17% while the -10 dB bandwidth reaches 20%. The simulated gain is 18.4 dBi at 17 GHz. The designed antenna has been manufactured and measured in the Escuela Politécnica Superior at Universidad Autónoma de Madrid, showing a severely mismatched response. In simulations, the antenna has proven to be very sensitive to changes in the vertical input transition. Hence, a new design with a horizontal input transition is proposed. Such transition is more stable and is backed by successful experiences in previous works. The new prototype has been manufactured, achieveing more than 15.8% -10 dB matching bandwidth. Due to manufacturing limitations, the measured gain falls to 16.7 dBi at 17 GHz