Diseño de agrupaciones de antenas alimentadas con redes corporativas en tecnología de guía de onda

Tradicionalmente en el grupo de investigación RFCAS se han diseñado redes de alimentación de diversa índole, como son por ejemplo redes tipo serie o paralelo en tecnología microstrip o SIW. Sin embargo, para el caso de redes en tecnología de guía de onda la distribución tipo serie ha sido la más utilizada debido al ahorro de espacio que conlleva frente a la de tipo paralelo. De hecho, agrupaciones en paralelo distribuidas sobre el plano E ni siquiera han sido estudiadas. En el presente documento se ha procedido a analizar el comportamiento de distintas agrupaciones de antenas alimentadas por redes corporativas en tecnología de guía de onda. Se ha partido de la hipótesis de que el elemento unitario de las agrupaciones a estudiar se iba a comportar de manera adecuada cuando fuera replicado a lo largo de las diferentes estructuras que se han propuesto. De este modo se han podido extraer las conclusiones pertinentes sobre el comportamiento de las distintas redes diseñadas, independientemente del tipo de array que ha sido alimentado con ellas. Como elemento radiante se ha tomado uno perteneciente al grupo de investigación RFCAS ya diseñado y medido, el cual consiste en un parche circular microstrip apilado sobre una ranura rectangular microstrip para polarización lineal, que es alimentado a través de una guía de onda rectangular estándar WR-51. El diseño ha sido optimizado para la porción superior de la banda Ku del espectro radioeléctrico, de 16 a 18 GHz. Las estructuras en guía que se han propuesto han sido dos arrays lineales de 4 elementos, uno de ellos en plano H y el otro en plano E. Por lo tanto, gran parte del trabajo que se ha realizado ha tratado sobre el modelado de los distintos elementos de que se componen las redes de alimentación corporativas que alimentan dichos arrays, tales como uniones en T, en Y o codos en ambos planos. Todos los diseños planteados han sido construidos y medidos como paso posterior a la etapa de diseño. Finalmente, se ha diseñado una transición de guía de onda a conector coaxial para el caso del plano H, debido a la imposibilidad de cargar todos los puertos de la red a su impedancia característica para medirla en transmisión. Dicha transición ha sido replicada por 4 en una única pieza, lo que ha permitido caracterizar el array de elementos radiantes y la red de alimentación corporativa por separado. Con todo esto se ha realizado un estudio muy completo de los elementos de que se compone la antena plano H, y se ha verificado si el parámetro de adaptación de la citada antena se corresponde con el de la red de alimentación y el array de parches sobre ranuras medidos por separado.Several kind of feeding networks had been conventionally designed in RFCAS research group, such as serial or parallel network based on microstrip or substrate integrated waveguide (SIW) technology. Nevertheless, waveguide technology had been mainly used in serial feeding structures design owing to their space-saving properties in comparison to parallel example. As a matter of fact, E-plane parallel arrays had been never studied at RFCAS. In the present document different array antenna configurations fed by corporate waveguide feeding networks are analyzed. As a starting point, it is assumed that the single element of all array antennas would behave appropriately when it is replicated along the different proposed structures. This way, conclusions about all designed networks had been drawn regardless of which array antenna type was being fed. The selected radiating element belongs to RFCAS and it is already designed and measured. It consists of a circular microstrip patch stacked to a microstrip slot fed by a standard WR-51 waveguide for linear polarization. Designed antenna is optimized for upper Ku band part, from 16 to 18 GHz. Proposed waveguide structures are two 4-element linear arrays, one at H-plane and E-plane respectively. Therefore, outlining both E-plane and H-plane elements such as Tjunctions, Y-junctions and bends became the major part of the developed work. All the presented designs have been manufactured and measured. Finally, a coaxial to waveguide transition has been designed for H-plane antenna due to output load matching is not physically possible. This transition is repeated 4 times in a single piece, so both array of radiating elements and corporate waveguide feeding network are accessible to be measured separately. All this leads to an exhaustive characterization of the elements which form part of the complete H-plane array antenna. Adaptation coefficient is measured from complete antenna input port. It is also estimated by joining both array of radiating elements and corporate waveguide feeding network Sparameters so this measures can be validated

Gain-Reconfigurable Hybrid Metal-Graphene Printed Yagi Antenna for Energy Harvesting Applications

This paper presents a hybrid metal-graphene printed Yagi antenna with reconfigurable gain that operates in the 5.5-GHz band. The balun and the driven elements are made of copper, while the directors are made of graphene. The graphene acts as a tunable material in the design. By switching the conductivity of the graphene, it is achieved a similar effect to adding or subtracting directors in the antenna. Hence the gain of the printed Yagi can be easily controlled. This could be of special interest in RF energy harvesting in the design of reconfigurable harvesting elements.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

ARAHAN PENGEMBANGAN RUANG WILAYAH METROPOLITAN BANDUNG

Abstrak : Tulisan ini akan menguraikan arahan sebagai masukan dalam mewujudkan struktur ruang wilayah Metropolitan Bandung yang mempertimbangkan upaya antisipasi permasalahan dan pencapaian kondisi yang lebih baik. Arahan pengembangan yang diusulkan tetap mengacu pada-aspek penting berupa kebijakan pengembangan wilayah (nasional, propinsi, kabupaten/kota bersangkutan); serta perkiraan perkembangan kegiatan dan penduduk pada masa mendatang. Kata kunci : ruang, metropolitan, Bandun

Evaluation of a Planar Reconfigurable Phased Array Antenna Driven by a Multi-Channel Beamforming Module at Ka Band

© 2021 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 worksIn this paper, a planar active phased array antenna demonstration with linear polarization (LP) at Ka Band (28-30 GHz) is presented. The proof of concept is carried out to evaluate the possible problems that may arise, to analyze possible calibration stages and to assess the viability of the integration of an active system with a Multi-Channel Beamforming Module (MCBM). To fulfill this task an 8times 8-element planar array arranged in column subarrays of 1times 8 elements for 1D beam steering is proposed. The single element consists of a printed circular patch connected to a microstrip feeding line through metallic vias in a multilayered structure. Both the amplitude and phase distributions are performed by a commercial integrated circuit (IC) designed for transmission purposes, from the common port to each of the 8 output ports. Thus, an evaluation of the IC performance is also included within this work. Despite the inherent amplitude and phase feeding errors of the IC, the beam-steering accuracy of the system is reasonable. A nice correspondence between the simulated and measured 8times 8-element array beam steering directions is obtained, with errors below 1° in the steering of the beamThis work was supported in part by the Spanish Government, Ministry of Economy, National Program of Research, Development and Innovation through the Project FUTURE RADIO ’’Radio systems and technologies for high capacity terrestrial and satellite communications in an hyperconnected world’’ under Grant TEC2017-85529-C3-1-R, and in part by the Project JETSTREAM ’’Desarrollo de una antena banda KA embarcada para la prestación de servicios de acceso a Internet por satélite en aviación comercial’’ in collaboration with TELNET Redes Inteligentes S.A. under Grant RTC-2015-3495-

Ka Band active array antenna for mobile satellite communications

This paper describes a modular active antenna for satellite communications in the K/Ka band. The application is thought for mobile satellite communications and internet links, mainly for commercial airplanes. The impossibility to build full active antennas, including amplifiers in all the elements, leads to a modular semi active antenna. Here the module is a small subarray with complete phase control in the elements. The phase control is made with ad-hoc phase shifters giving the minimum losses. Only two-bit control has been selected to perform phase shifters associated to a circular polarization radiating element. The feeding network has been selected to minimise the losses and the gap waveguide has been designed to perform the network. The radiating element is a circular double patch fed into two points to obtain circular polarization. The entire prototype has been designed in LTCC substrate to minimise the losses and stabilise the structure

Mechanically reconfigurable linear phased array antenna based on single-block waveguide reflective phase shifters with tuning screws

This work presents the design and prototyping of a reconfigurable phased array in Ku band (16 to 18 GHz) implemented in waveguide technology. The design is based on the use of a novel seamless waveguide module integrating four reconfigurable phase shifters to adjust the relative phase shift between the unitary elements of a linear array, which are illuminated uniformly by a corporate waveguide feeding network. The phase shifters are implemented by a 90º hybrid coupler in waveguide technology where two of its ports are loaded with a tunable reactive load, implemented in this proof of concept with a tuning screw. The four phase shifters have been manufactured in a single part using direct metal laser sintering, avoiding the losses related to bad electric contacts and misalignments associated to multipart devices. This also simplifies the assembly of the full phased array, leading to a modular approach with three parts whose design can be addressed separately. The experimental results for the complete array antenna show great performance and demonstrate that the main-lobe of the radiation pattern can be effectively scanned continuously between the angles - 25º and 25º, with a high efficiency in the whole design band thanks to the proposed waveguide implementationThis work was supported by the Spanish Government, Agencia Estatal de Investigación, Fondo Europeo de Desarrollo Regional: AEI/FEDER, UE, under Grant TEC2016-76070-C3-1-

Multi-probe measurement system based on single-cut transformation for fast testing of linear arrays

This paper introduces a near-field measurement system concept for the fast testing of linear arrays suited for mass production scenarios where a high number of nominally identical antennas needs to be measured. The proposed system can compute the radiation pattern, directivity and gain on the array plane, as well as the array complex feeding coefficients in a matter of seconds. The concept is based on a multi-probe antenna array arranged in a line which measures the near field of the antenna under test in its array plane. This linear measurement is postprocessed with state-of-the-art single-cut transformation techniques. To compensate the lack of full 3D information, a previous complete characterization of a “Gold Antenna” is performed. This antenna is nominally identical to the many ones that will be measured with the proposed system. Therefore, the data extracted from this full characterization can be used to complement the postprocessing steps of the single-cut measurements. An X-band 16-probe demonstrator of the proposed system is implemented and introduced in this paper, explaining all the details of its architecture and operation steps. Finally, some measurement results are given to compare the developed demonstrator with traditional anechoic measurements, and show the potential capabilities of the proposed concept to perform fast and reliable measurements.This work was funded by Indra Sistemas S.A. and by the Spanish Government, Ministry of Economy, National Program of Research, Development and Innovation through the project FUTURERADIO “Radio systems and technologies for high capacity terrestrial and satellite communications in an hyperconnected world” (project number TEC2017-85529-C3-1-R)

New pattern reconfiguration techniques for planar array antennas at millimetric bands

It is increasingly common for new communications systems for satellite or radar applications to require more versatile antenna designs, capable of reorienting the radiation pattern in different directions with sufficient precision or changing the polarisation scheme in a controlled and agile manner. In the specific case of SATellite COMmunications (SATCOM), the migration to the use of the new Ka and K frequency bands for transmit and receive schemes, respectively, has allowed to increase the channel capacity considerably, achieving much higher transmission rates than predecessor systems. These new frequency bands have meant a revision of the antenna designs available in the previously used satellite frequency bands (S, X or Ku band), as well as a new technological challenge in terms of design, manufacturing, and measurement. Of particular relevance is that this increase in frequency of satellite systems has unlocked the possibility of using antenna array systems (mainly planar) to achieve very high gain antennas with beam reconfiguration capability, so that they can be used as transmit/receive terminals in the ground segment in mobile satellite communications applications (“SATCOM On The Move” or SOTM), mainly due to two factors: - The physical antenna aperture size (for a given gain) is sufficiently reduced in these bands to make the development of high gain array antennas for mobile terminals feasible. - In addition, there is another limiting factor when it comes to exploiting higher frequency bands for reconfigurable antenna arrays, and that is the space available to integrate the necessary RF circuitry (phase shifters and/or variable gain amplifiers). Many beam reconfiguration methods present in the more classical literature will not fit at the radiating element level. - The above points have redirected market demands, and by extension, the industry trend in antenna design for SOTM communications. This is evidenced by the numerous companies offering RF Integrated Circuits (RFICs) in their catalogues for application in the design of active antenna arrays, which can be integrated into such antennas. These circuits incorporate independent chains of digital phase shifters and variable gain amplifiers for control of pointing, polarisation, Side Lobe Level (SLL), etc. The development and affordability of such Integrated Circuits (ICs) has led to the transition of such type of antennas from military to the civilian sector, in which they are maturing. In fact, IC developers have started to offer their own active antenna array solutions, based on their own circuits, and on printed planar technology. However, while there are many such antenna publications in the literature, few of them apply a theoretical/empirical analysis of the integrated circuits themselves, nor do they reveal information about the various errors that can arise from them. Therefore, one of the main objectives of this doctoral thesis is to try to offer a simple analysis model capable of characterising with sufficient accuracy the integrated circuits that are shaping the current trend in active antenna design. Ultimately, this model should be able to offer the possibility of calibrating the response of the chip in amplitude and phase to suit external conditions (e.g., the bandwidth of the signal to be transmitted/received, the coupling matrix of the radiating interface, the pointing to be generated, the level of secondary lobes to be implemented, etc.). In addition to the characterisation of the chip itself, an exhaustive study is carried out of the radiation properties of various antenna arrays of different types (8x8 elements with linear polarisation and 2x2 elements with switchable circular polarisation) connected to one of these integrated circuits. In this way, it will be possible to infer to what extent the errors present on the chip affect each of the radiation parameters of the antenna under analysis, and which radiation parameters are more critical to these errors depending on the paradigm of the antenna. On the other hand, the decision is taken to build on and extend the experience developed over the years in the Radiation Group (GR) in the design of planar antennas fed by Radial Line for application to SATCOM in the ground segment. In this second part, the active pattern reconfiguration scheme is abandoned to explore the possibilities that Radial Line Patch Antenna (RLPA) designs offer in the K receive band (and for circular polarisation). At the cost of introducing a frequency-dependent phase error in the aperture (whose slope increases with aperture size), the complexity of the feed network is relaxed. Furthermore, subdividing the highgain antenna design into several antenna subarrays relaxes the complexity of the antenna feeding network without increasing the phase error of the antenna. On this basis, different beam reconfiguration techniques (all of them fixed) are explored with the above-described feeding scheme. The first one achieves to adjust the radiated phase of each of the radiating elements to implement a uniform distribution by rotating the radiating elements. The proposed method is purely geometrical and does not increase the computational cost of implementation in any aspect. Moreover, it has the property of indirectly implementing a partial sequential rotation between the radiating elements, so that the axial ratio of the design will be improved. From here, the properties of these antennas are explored when the beam is steered from the uniform phase distribution. In addition, a different scheme of feeding the radiating interface by means of a waveguide feeder is proposed, which from a WR-42 standard waveguide manages to generate the TM01 mode in an intermediate circular guide that excites the radial mode in the radial line. This provides a low-loss interface to the distribution network between antenna subarrays. With all this, the thesis is sub-divided into two distinct parts, exploring either active design solutions or passive solutions, both of which are described in the previous paragraphs. RESUMEN Cada vez es más habitual que los nuevos sistemas de comunicaciones para aplicaciones satelitales o de radar requieran de diseños de antenas más versátiles, capaces de reorientar el diagrama de radiación hacia distintas direcciones con suficiente precisión o de cambiar el esquema de polarización de manera ágil y controlada. En el caso concreto de las comunicaciones por satélite (SATCOM), la migración al uso de las nuevas bandas de frecuencias Ka y K para los esquemas de transmisión y recepción respectivamente, ha permitido incrementar la capacidad de canal considerablemente, logrando alcanzar tasas de transmisión mucho mayores que sistemas predecesores. Estas nuevas bandas de frecuencias han supuesto una revisión de los diseños de antena disponibles en las bandas de frecuencias satelitales previamente utilizadas (banda S, X o Ku), además de suponer un nuevo reto tecnológico en cuestiones de diseño, fabricación y medida. Es de especial relevancia que esta subida en frecuencia de los sistemas satelitales ha desbloqueado la posibilidad de emplear sistemas de agrupaciones de antenas (principalmente planas) para lograr antenas de muy alta ganancia con capacidad de reconfiguración de haz, de tal forma que puedan ser empleadas como terminales de transmisión/recepción en el segmento terreno en aplicaciones de comunicaciones móviles por satélite (SATCOM On The Move o SOTM), debido principalmente a dos factores: - El tamaño físico de apertura de antena (para una ganancia determinada) se reduce lo suficiente en estas bandas como para que el desarrollo de agrupaciones de antenas de alta ganancia para terminales móviles sea viable. - Además, existe otro factor limitante cuando se trata de explotar bandas de frecuencias más altas para agrupaciones de antenas reconfigurables, y es el espacio disponible para integrar la circuitería de RF necesaria (desfasadores y/o amplificadores de ganancia variable). Muchos métodos de reconfiguración de haz presentes en la literatura más clásica no van a caber a nivel de elemento radiante. - Los puntos anteriores han redirigido las demandas del mercado, y por extensión, la tendencia de la industria en materia de diseño de antenas para comunicaciones SOTM. Prueba de ello son las numerosas empresas que ofrecen en sus catálogos circuitos integrados de RF (RFIC) para su aplicación en el diseño de agrupaciones activas de antenas, los cuales sí que se van a poder integrar en este tipo de antenas. Estos circuitos incorporan cadenas independientes de desfasadores digitales y amplificadores de ganancia variable para control de apuntamiento, polarización, nivel de lóbulos secundarios, etc. El desarrollo y la asequibilidad de este tipo de circuitos integrados han provocado que este tipo de antenas pasen del sector militar al sector civil, en el que están madurando. De hecho, las empresas desarrolladoras de este tipo de circuitos integrados han empezado a ofrecer sus propias soluciones de agrupaciones activas de antenas, basadas en sus propios circuitos, y en tecnología plana impresa. No obstante, y aunque la publicación de antenas de esta índole en la literatura es cuantiosa, pocas de ellas aplican un análisis teórico/empírico sobre los propios circuitos integrados, ni desvelan información acerca de los distintos errores que de ellos se pueden desprender. Por ello, uno de los principales objetivos de la presente tesis doctoral es el de intentar ofrecer un modelo de análisis sencillo, que sea capaz de caracterizar con la suficiente precisión los circuitos integrados que están moldeando la tendencia actual de diseño de antenas activas. En última instancia, este modelo deberá ser capaz de ofrecer la posibilidad de calibrar la respuesta del chip en amplitud y fase para adecuarse a las condiciones ajenas a él (por ejemplo, la banda de la señal a transmitir/recibir, la matriz de acoplo de la interfaz radiante, el apuntamiento que se desee generar, el nivel de lóbulos secundarios que se desee implementar, etc). Además de la caracterización propia del chip, se realiza un estudio exhaustivo de las propiedades de radiación de varias agrupaciones de antenas de distinta índole (8x8 elementos con polarización lineal y 2x2 elementos con polarización circular conmutable) que se conecta a uno de estos circuitos integrados. De esta forma, se va a poder inferir hasta qué punto los errores presentes en el chip afectan a cada uno de los parámetros de radiación de la antena bajo análisis, y qué parámetros de radiación son más críticos a estos errores según el paradigma de dicha antena. Por otra parte, se toma la decisión de aprovechar y ampliar la experiencia desarrollada a lo largo de los años en el Grupo de Radiación (GR) en el diseño de antenas planas alimentadas en guía radial para su aplicación a aplicaciones SATCOM en el segmento terreno. En esta segunda parte, se abandona el esquema activo de reconfiguración de diagrama para explorar las posibilidades que los diseños de antenas de parche impresas alimentadas en guía radial ofrecen en la banda de recepción K (y para polarización circular). A costa de introducir un error de fase en la apertura dependiente de la frecuencia (y cuya pendiente aumenta con el tamaño de la misma) se relaja la complejidad de la red de alimentación. Además, subdividiendo el diseño de antena de alta ganancia en diversas sub-agrupaciones de antenas se logra relajar la complejidad de la red de alimentación de la antena sin incrementar el error de fase de la misma. Partiendo de esta base, se exploran diferentes técnicas de reconfiguración de haz (todas ellas fijas) con el esquema de alimentación anteriormente descrito. La primera de ellas logra ajustar la fase radiada de cada uno de los elementos radiantes para implementar una distribución uniforme mediante la rotación de dichos elementos radiantes. El método propuesto es puramente geométrico y no incrementa en ningún aspecto el coste computacional de implementación. Además, tiene la propiedad de indirectamente implementar una rotación secuencia parcial entre los elementos radiantes, de modo que la relación axial del diseño mejorará. A partir de aquí, se exploran las propiedades de estas antenas cuando el haz se desapunta a partir de la distribución uniforme de fase. Además, se propone un esquema diferente de alimentación de la interfaz radiante mediante un alimentador en guía de onda, que desde una guía WR-42 estándar logra generar el modo TM01 en una guía circular intermedia que excita el modo radial en la guía radial. De este modo, se tiene una interfaz de bajas pérdidas para la red de distribución entre sub-agrupaciones de antenas. Con todo esto, la tesis se sub-divide en dos partes diferenciadas, en las que se exploran las soluciones activas de diseño, o las soluciones pasivas, ambas descritas en los párrafos anteriores

Design of triangular-latticed subarray antenna fed by hexagonal radial line for K-band applications

A circularly polarized double-stacked patch subarray antenna fed by a hexagonal radial line with internal circular coupling patches is proposed. The antenna works at K band (19.7 GHz –20.2 GHz) with LHCP. On the one hand, the design approach consists of a coupling study based on the simulation of a periodic parallel-plate waveguide as a first approximation of the radial line. On the other hand, a phase compensation method by rotation is applied in order to adjust the radiating phase of each element of the subarray, which are separated 0.7λ0. Thus, the subarray is uniformly fed in terms of amplitude and phase. An axial ratio below 1 dB is achieved for the entire frequency band, with a gain of 24 dB and a total efficiency of 87%. The radial line has been modelled as a hexagon to perform this analysis in larger arrays in future design steps

Subarray activo para antenas de comunicaciones por satélite en banda Ka

This paper describes a modular active antenna for satellite communications in the K/Ka band. The application is thought for mobile satellite communications and internet links, mainly for commercial airplanes. The impossibility to build full active antennas including amplifiers in all the elements leads to a modular semi active antenna. Here the module is a small subarray with complete phase control in the elements. The phase control is made with ad-hoc phase shifters giving the minimum losses. Only two-bit control has been selected to perform phase shifters associated to a circular polarization radiating element. The feeding network has been selected to give the minimum losses and special ridge waveguide has been design to perform the network. The radiating element is a circular double patch fed in two points to obtain circular polarization. All the prototype has been designed in LTCC substrate to perform the minimum losses and stable structur