186 research outputs found
Novel ring resonator-based integrated photonic beamformer for broadband phased array receive antennas - part I: design and performance analysis
A novel optical beamformer concept is introduced that can be used for seamless control of the reception angle in broadband wireless receivers employing a large phased array antenna (PAA). The core of this beamformer is an optical beamforming network (OBFN), using ring resonator-based broadband delays, and coherent optical combining. The electro-optical conversion is performed by means of single-sideband suppressed carrier modulation, employing a common laser, Mach-Zehnder modulators, and a common optical sideband filter after the OBFN. The unmodulated laser signal is then re-injected in order to perform balanced coherent optical detection, for the opto-electrical conversion. This scheme minimizes the requirements on the complexity of the OBFN, and has potential for compact realization by means of full integration on chip. The impact of the optical beamformer concept on the performance of the full receiver system is analyzed, by modeling the combination of the PAA and the beamformer as an equivalent two-port RF system. The results are illustrated by a numerical example of a PAA receiver for satellite TV reception, showing thatâwhen properly designedâthe beamformer hardly affects the sensitivity of the receiver
Development of a broadband and squint-free Ku-band phased array antenna system for airborne satellite communications
Novel avionic communication systems are required for various purposes, for example to increase the flight safety and operational integrity as well as to enhance the quality of service to passengers on board. To serve these purposes, a key technology that is essential to be developed is an antenna system that can provide broadband connectivity within aircraft cabins at an affordable price. Currently, in the European Commission (EC) 7th Framework Programme SANDRA project (SANDRA, 2011), a development of such an antenna system is being carried out. The system is an electronically-steered phased-array antenna (PAA) with a low aerodynamic profile. The reception of digital video broadcasting by satellite (DVB-S) signal which is in the frequency range of 10.7-12.75 GHz (Ku-band) is being considered. In order to ensure the quality of service provided to the passengers, the developed antenna should be able to receive the entire DVB-S band at once while complying with the requirements of the DVB-S system (Morello & Mignone, 2006). These requirements, as will be explained later, dictate a broadband antenna system where the beam is squint-free, i.e. no variation of beam pointing direction for all the frequencies in the desired band. Additionally, to track the satellite, the seamless tunability of the beam pointing direction of this antenna is also required. In this work, a concept of optical beamforming (Riza & Thompson, 1997) is implemented to provide a squint-free beam over the entire Ku-band for all the desired pointing directions. The optical beamformer itself consists of continuously tunable optical delay lines that enable seamless tunability of the beam pointing direction
Photonic Vector Processing Techniques for Radiofrequency Signals
[EN] The processing of radiofrequency signals using photonics means is a discipline that appeared almost at the same time as the laser and the optical fibre. Photonics offers the capability of managing broadband radiofrequency (RF) signals thanks to its low transmission attenuation, a variety of linear and non-linear phenomena and, recently, the potential to implement integrated photonic subsystems. These features open the door for the implementation of multiple functionalities including optical transportation, up and down frequency conversion, optical RF filtering, signal multiplexing, de-multiplexing, routing and switching, optical sampling, tone generation, delay control, beamforming and photonic generation of digital modulations, and even a combination of several of these functionalities. This thesis is focused on the application of vector processing in the optical domain to radiofrequency signals in two fields of application: optical beamforming, and photonic vector modulation and demodulation of digital quadrature amplitude modulations. The photonic vector control enables to adjust the amplitude and phase of the radiofrequency signals in the optical domain, which is the fundamental processing that is required in different applications such as beamforming networks for direct radiating array (DRA) antennas and multilevel quadrature modulation.
The work described in this thesis include different techniques for implementing a photonic version of beamforming networks for direct radiating arrays (DRA) known as optical beamforming networks (OBFN), with the objectives of providing a precise control in terrestrial applications of broadband signals at very high frequencies above 40 GHz in communication antennas, optimizing the size and mass when compared with the electrical counterparts in space application, and presenting new photonic-based OBFN functionalities. Thus, two families of OBFNs are studied: fibre-based true time delay architectures and integrated networks. The first allow the control of broadband signals using dispersive optical fibres with wavelength division multiplexing techniques and advanced functionalities such as direction of arrival estimation in receiving architectures. In the second, passive OBFNs based on monolithically-integrated Optical Butler Matrices are studied, including an ultra-compact solution using optical heterodyne techniques in silicon-on-insulator (SOI) material, and an alternative implementing a homodyne counterpart in germanium doped silica material.
In this thesis, the application of photonic vector processing to the generation of quadrature digital modulations has also been investigated. Multilevel modulations are based on encoding digital information in discrete states of phase and amplitude of an electrical signal to enhance spectral efficiency, as for instance, in quadrature modulation. The signal process required for generating and demodulating this kind of signals involves vector processing (phase and amplitude control) and frequency conversion. Unlike the common electronic or digital implementation, in this thesis, different photonic based signal processing techniques are studied to produce digital modulation (photonic vector modulation, PVM) and demodulation (PVdM). These techniques are of particular interest in the case of broadband signals where the data rate required to be managed is in the order of gigabit per second, for applications like wireless backhauling of metro optical networks (known as fibre-to-the-air). The techniques described use optical dispersion in optical fibres, wavelength division multiplexing and photonic up/down conversion. Additionally, an optical heterodyne solution implemented monolithically in a photonic integrated circuit (PIC) is also described.[ES] El procesamiento de señales de radiofrecuencia (RF) utilizando medios fotĂłnicos es una disciplina que apareciĂł casi al mismo tiempo que el lĂĄser y la fibra Ăłptica. La fotĂłnica ofrece la capacidad de manipular señales de radiofrecuencia de banda ancha, una baja atenuaciĂłn, procesados basados en una amplia variedad de fenĂłmenos lineales y no lineales y, recientemente, el potencial para implementar subsistemas fotĂłnicos integrados. Estas caracterĂsticas ofrecen un gran potencial para la implementaciĂłn de mĂșltiples funcionalidades incluyendo transporte Ăłptico, conversiĂłn de frecuencia, filtrado Ăłptico de RF, multiplexaciĂłn y demultiplexaciĂłn de señales, encaminamiento y conmutaciĂłn, muestreo Ăłptico, generaciĂłn de tonos, lĂneas de retardo, conformaciĂłn de haz en agrupaciones de antenas o generaciĂłn fotĂłnica de modulaciones digitales, e incluso una combinaciĂłn de varias de estas funcionalidades. Esta tesis se centra en la aplicaciĂłn del procesamiento vectorial en el dominio Ăłptico de señales de radiofrecuencia en dos campos de aplicaciĂłn: la conformaciĂłn Ăłptica de haces y la modulaciĂłn y demodulaciĂłn vectorial fotĂłnica de señales digitales en cuadratura. El control fotĂłnico vectorial permite manipular la amplitud y fase de las señales de radiofrecuencia en el dominio Ăłptico, que es el procesamiento fundamental que se requiere en diferentes aplicaciones tales como las redes de conformaciĂłn de haces para agrupaciones de antenas y en la modulaciĂłn en cuadratura.
El trabajo descrito en esta tesis incluye diferentes tĂ©cnicas para implementar una versiĂłn fotĂłnica de las redes de conformaciĂłn de haces de en agrupaciones de antenas, conocidas como redes Ăłpticas de conformaciĂłn de haces (OBFN). Se estudian dos familias de redes: arquitecturas de retardo en fibra Ăłptica y arquitecturas integradas. Las primeras permiten el control de señales de banda ancha utilizando fibras Ăłpticas dispersivas con tĂ©cnicas de multiplexado por divisiĂłn de longitud de onda y funcionalidades avanzadas tales como la estimaciĂłn del ĂĄngulo de llegada de la señal en la antena receptora. En la segunda, se estudian redes de conformaciĂłn pasivas basadas en Matrices de Butler Ăłpticas integradas, incluyendo una soluciĂłn ultra-compacta utilizando tĂ©cnicas Ăłpticas heterodinas en silicio sobre aislante (SOI), y una alternativa homodina en sĂlice dopado con germanio.
En esta tesis, tambiĂ©n se han investigado tĂ©cnicas de procesado vectorial fotĂłnico para la generaciĂłn de modulaciones digitales en cuadratura. Las modulaciones multinivel codifican la informaciĂłn digital en estados discretos de fase y amplitud de una señal elĂ©ctrica para aumentar su eficiencia espectral, como por ejemplo la modulaciĂłn en cuadratura. El procesado necesario para generar y demodular este tipo de señales implica el procesamiento vectorial (control de amplitud y fase) y la conversiĂłn de frecuencia. A diferencia de la implementaciĂłn electrĂłnica o digital convencional, en esta tesis se estudian diferentes tĂ©cnicas de procesado fotĂłnico tanto para la generaciĂłn de modulaciones digitales (modulaciĂłn vectorial fotĂłnica, PVM) como para su demodulaciĂłn (PVdM). Esto es de particular interĂ©s en el caso de señales de banda ancha, donde la velocidad de datos requerida es del orden de gigabits por segundo, para aplicaciones como backhaul inalĂĄmbrico de redes Ăłpticas metropolitanas (conocida como fibra hasta el aire). Las tĂ©cnicas descritas se basan en explotar la dispersiĂłn cromĂĄtica de la fibra Ăłptica, la multiplexaciĂłn por divisiĂłn de longitud de onda y la conversiĂłn en frecuencia. AdemĂĄs, se presenta una soluciĂłn heterodina implementada monolĂticamente en un circuito integrado fotĂłnico (PIC).[CA] El processament de senyals de radiofreqĂŒĂšncia (RF) utilitzant mitjans fotĂČnics Ă©s una disciplina que va aparĂšixer gairebĂ© al mateix temps que el lĂ ser i la fibra ĂČptica. La fotĂČnica ofereix la capacitat de manipular senyals de radiofreqĂŒĂšncia de banda ampla, una baixa atenuaciĂł, processats basats en una Ă mplia varietat de fenĂČmens lineals i no lineals i, recentment, el potencial per implementar subsistemes fotĂČnics integrats. Aquestes caracterĂstiques ofereixen un gran potencial per a la implementaciĂł de mĂșltiples funcionalitats incloent transport ĂČptic, conversiĂł de freqĂŒĂšncia, filtrat ĂČptic de RF, multiplexaciĂł i demultiplexaciĂł de senyals, encaminament i commutaciĂł, mostreig ĂČptic, generaciĂł de tons, lĂnies de retard, conformaciĂł de feix en agrupacions d'antenes i la generaciĂł fotĂČnica de modulacions digitals, i fins i tot una combinaciĂł de diverses d'aquestes funcionalitats. Aquesta tesi es centra en l'aplicaciĂł del processament vectorial en el domini ĂČptic de senyals de radiofreqĂŒĂšncia en dos camps d'aplicaciĂł: la conformaciĂł ĂČptica de feixos i la modulaciĂł i demodulaciĂł vectorial fotĂČnica de senyals digitals en quadratura. El control fotĂČnic vectorial permet manipular l'amplitud i la fase dels senyals de radiofreqĂŒĂšncia en el domini ĂČptic, que Ă©s el processament fonamental que es requereix en diferents aplicacions com ara les xarxes de conformaciĂł de feixos per agrupacions d'antenes i en modulaciĂł multinivell.
El treball descrit en aquesta tesi inclou diferents tĂšcniques per implementar una versiĂł fotĂČnica de les xarxes de conformaciĂł de feixos en agrupacions d'antenes, conegudes com a xarxes ĂČptiques de conformaciĂł de feixos (OBFN), amb els objectius de proporcionar un control precĂs en aplicacions terrestres de senyals de banda ampla a freqĂŒĂšncies molt altes per sobre de 40 GHz en antenes de comunicacions, optimitzant la mida i el pes quan es compara amb els homĂČlegs elĂšctrics en aplicacions espacials, i la presentaciĂł de noves funcionalitats fotĂČniques per agrupacions d'antenes. Per tant, s'estudien dues famĂlies de OBFNs: arquitectures de retard en fibra ĂČptica i arquitectures integrades. Les primeres permeten el control de senyals de banda ampla utilitzant fibres ĂČptiques dispersives amb tĂšcniques de multiplexaciĂł per divisiĂł en longitud d'ona i funcionalitats avançades com ara l'estimaciĂł de l'angle d'arribada del senyal a l'antena receptora. A la segona, s'estudien xarxes de conformaciĂł passives basades en Matrius de Butler ĂČptiques en fotĂČnica integrada, incloent una soluciĂł ultra-compacta utilitzant tĂšcniques ĂČptiques heterodinas en silici sobre aĂŻllant (SOI), i una alternativa homodina en sĂlice dopat amb germani.
D'altra banda, tambĂ© s'ha investigat en aquesta tesi tĂšcniques de processament vectorial fotĂČnic per a la generaciĂł de modulacions digitals en quadratura. Les modulacions multinivell codifiquen la informaciĂł digital en estats discrets de fase i amplitud d'un senyal elĂšctric per augmentar la seva eficiĂšncia espectral, com ara la modulaciĂł en quadratura. El processat necessari per generar i desmodular aquest tipus de senyals implica el processament vectorial (control d'amplitud i fase) i la conversiĂł de freqĂŒĂšncia. A diferĂšncia de la implementaciĂł electrĂČnica o digital convencional, en aquesta tesi s'estudien diferents tĂšcniques de processament fotĂČnic tant per a la generaciĂł de modulacions digitals (modulaciĂł vectorial fotĂČnica, PVM) com per la seva demodulaciĂł (PVdM). AixĂČ Ă©s de particular interĂšs en el cas de senyals de banda ampla, on la velocitat de dades requerida Ă©s de l'ordre de gigabits per segon, per a aplicacions com backhaul sense fils de xarxes ĂČptiques metropolitanes (coneguda com fibra fins l'aire). Les tĂšcniques descrites es basen en explotar la dispersiĂł cromĂ tica de la fibra ĂČptica, la multiplexaciĂł per divisiĂł en longitud d'ona i la conversiĂł en freqĂŒĂšncia. A mĂ©s, es presePiqueras RuipĂ©rez, MĂ. (2016). Photonic Vector Processing Techniques for Radiofrequency Signals [Tesis doctoral no publicada]. Universitat PolitĂšcnica de ValĂšncia. https://doi.org/10.4995/Thesis/10251/63264TESI
Silicon Photonics Optical Beamformer for Broadband Phased Array Antennas
Este projecto tem como objectivo o estudo, desenho e simulação de um beamformer Ăłptico, a operar na banda Ka (26 - 40 GHz) implementado num circuito fotĂłnico integrado. Este dispositivo deve ser capaz de gerar atrasos TTD (True Time Delay) de modo a evitar deformaçÔes de feixe, denominadas beamsquint, que afectam negativamente a qualidade do sinal transmitido. Esta funcionalidade tem como objectivo melhorar a performance de sistemas baseados em agrupamentos de antenas (Phased Array Antennas) para sinais com elevada largura de banda. Outro aspecto importante do projecto Ă© a integração do circuito Ăłptico num chip fotĂłnico baseado na tecnologia de fotĂłnica integrada em SilĂcio, que permite o fabrico de dispositivos Ăłpticos compactos e de baixo custo.This project proposes the design of a Photonic Integrated Circuit, or PIC, Optical Beaformer for broadband Phased Array Antennas, or PAA, operating in the Ka band (26 - 40 GHz). The beamformer circuit should implement a True Time Delay device that enables seamless phase tuning for each radiating element that is independent from frequency. The frequency independence of the generated delays avoids a recurring phenomenon on PAA systems known as beamsquint, which consists in deformation of the array radiation pattern that deteriorates the quality of the transmitted signal. Therefore, by eliminating beamsquint, this technology should allow PAA based systems to be used in broadband communications, which are becoming evermore pervasive, due to modern day demands for high-speed data tranfer. This project also aims to take advantage of recent integrated phtonics techonology, in order to fabricate compact and cheaper optical circuit devices
Performance issues with photonic beamformers
A photonic beamformer is presented, having smooth behavior. Third-order nonlinearities, resulting from its optoelectronic components, are investigated, with emphasis on their impact on the contrast of imaging radars. This contrast is shown to be severely limited by the induced RF nonlinearities. Limitations on the allowable modulation index are studied for linearly-chirped pulses returned from clutter
Photonic wideband phased array: an optical time steered antenna based on a new true time delay unit
LâattivitĂ di ricerca svolta durante il corso di dottorato e descritta dettagliatamente allâinterno della tesi Ăš stata diretta al progetto di una innovativa rete ottica di formazione del fascio per antenne a schiera a banda larga esenti dal fenomeno del beam squint.
La rete di formazione del fascio proposta Ăš basata sullâutilizzo di un chip ottico integrato modulare che consente di realizzare il True Time Delay implementando switched delay lines.
Le caratteristiche del sistema ne consentono lâutilizzo in architetture ad array e a subarray, e la sua modularitĂ rende possibile, in principio, il pilotaggio del sistema radiante, integrando in un unico componente le linee di ritardo di ciascun elemento della schiera.
Nella sua prima parte la tesi di dottorato introduce alle antenne ad alte prestazioni richieste dalle moderne applicazioni, focalizzando lâattenzione sui Phased Array, sistemi radianti destinati a svolgere un ruolo di primo piano grazie alla loro flessibilitĂ e potenzialitĂ . Unâanalisi ragionata delle soluzioni proposte in letteratura viene, quindi, proposta al fine di evidenziare i principi di funzionamento e le principali problematiche connesse allâimplementazione di reti ottiche di formazione del fascio. Inoltre, vengono descritte e discusse le architetture ottiche utilizzate sia per il controllo della fase che per il controllo del ritardo.
Successivamente viene presentata la nuova unitĂ ottica integrata di tipo True Time Delay. Le configurazioni di utilizzo del chip ottico studiate e messe a punto durante gli anni del corso di dottorato vengono presentate nel dettaglio, chiarendo le scelte e le strategie di progetto utilizzate in modo da ottimizzare le prestazioni del sistema. Viene presentato il progetto di un prototipo di antenna a schiera basato sul nuovo modulo True Time Delay e un modello accurato dellâintero sistema, implementato allo scopo di verificare il funzionamento dellâantenna e determinarne le prestazioni.
Il modello sviluppato tiene in conto delle reali caratteristiche dei dispositivi disponibili in commercio da utilizzarsi allâinterno della rete e del sistema radiante, degli inevitabili errori realizzativi relativi a ciascun componente e delle caratteristiche peculiari del nuovo modulo di ritardo.
Per compensare gli effetti degli errori suddetti Ăš stata prevista allâinterno della rete unâunitĂ di compensazione. Per rendere semplice ed efficace determinarne i parametri Ăš stato sviluppato un algoritmo evolutivo capace di sfruttare al meglio le potenzialitĂ dellâunitĂ cosĂŹ da evitare inutili complessitĂ .
Infine, viene proposta una nuova architettura, interamente ottica, di una rete di formazione del fascio per antenne a schiera capaci di irradiare sia fasci somma che fasci differenza beam squint free
Design and Optimization of Photonics-Based Beamforming Networks for Ultra-Wide mmWave-Band Antenna Arrays
In this chapter, we review the worldwide progress referred to designing optical beamforming networks intended to the next-generation ultra-wideband millimeter-wave phased array antennas for incoming fifth-generation wireless systems, which in recent years is under the close attention of worldwide communication community. Following the tendency, we study in detail the design concepts below true-time-delay photonics beamforming networks based on switchable or continuously tunable control. Guided by them, we highlight our NI AWRDE CAD-based simulation experiments in the frequency range of 57â76Â GHz on design of two 16-channel photonics beamforming networks using true-time-delay approach. In the first scheme of the known configuration, each channel includes laser, optical modulator, and 5-bit binary switchable chain of optical delay lines. The second scheme has an optimized configuration based on only 3-bit binary switchable chain of optical delay lines in each channel, all of which are driven by four lasers with wavelength division multiplexing and a common optical modulator. In the result, the novel structural and cost-efficient configuration of microwave-photonics beamforming network combining wavelength division multiplexing and true-time-delay techniques is proposed and investigated
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Modular coherent photonic-aided payload receiver for communications satellites
Ubiquitous satellite communications are in a leading position for bridging the digital divide. Fulfilling such a mission will require satellite services on par with fibre services, both in bandwidth and cost. Achieving such a performance requires a new generation of communications payloads powered by large-scale processors, enabling a dynamic allocation of hundreds of beams with a total capacity beyond 1Â Tbit sâ1. The fact that the scale of the processor is proportional to the wavelength of its signals has made photonics a key technology for its implementation. However, one last challenge hinders the introduction of photonics: while large-scale processors demand a modular implementation, coherency among signals must be preserved using simple methods. Here, we demonstrate a coherent photonic-aided receiver meeting such demands. This work shows that a modular and coherent photonic-aided payload is feasible, making way to an extensive introduction of photonics in next generation communications satellites
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