MASTER IN SIGNAL THEORY AND COMMUNICATIONS MASTER’S THESIS DESIGN AND CHARACTERIZATION OF W-BAND RADAR COMPONENTS MARTA FERRERAS MAYO 2017 MASTER’S THESIS Title: Design and Characterization of W-Band Radar Components Author: Marta Ferreras Mayo Tutor: Jes´us Grajal de la Fuente Department: Se˜nales, Sistemas y Radiocomunicaciones Group: Grupo de Microondas y Radar COMPOSITION OF THE TRIBUNAL President: Mariano Garc´ıaOtero Vocal: Jos´e Manuel Riera Sal´ıs Secretary: Manuel Sierra Casta˜ner Substitute: Pedro Zufiria Zatarain Date of defense and evaluation: 25th July 2017 Grading: 10-MH UNIVERSIDAD POLITECNICA´ DE MADRID ESCUELA TECNICA´ SUPERIOR DE INGENIEROS DE TELECOMUNICACION´ MASTER IN SIGNAL THEORY AND COMMUNICATIONS MASTER’S THESIS DESIGN AND CHARACTERIZATION OF W-BAND RADAR COMPONENTS MARTA FERRERAS MAYO 2017 Abstract This Master’s Thesis summarizes the work that has been performed in the frame of the SPADERADAR-CM Project for the ultimate purpose of developing a W-band space debris radar operating at 94 GHz. The main goal of this type of radars consists of detecting and tracking particles, with sizes ranging from 1 to 10 cm, that are orbiting around the Earth at speeds up to 15 km/s and that could cause severe damage in case of collision against manned spacecraft. Particularly, the work performed within the realization of this Thesis has contributed to the progress of the space debris radar in several aspects of the hardware architecture of the system. On one side, part of the work has been concerned with the characterization and integration of the millimeter-wave receiving subsystem of the radar. On the other side, different pre-designs for the antenna system have been simulated and analyzed, and the performance of a reflectarray, that could be used in the future to obtain electronic scanning, has been characterized. Apart from studying the available literature, the utilized methodology has required the familiarization with measurement equipment to characterize devices at millimeter wavelengths. Furthermore, the use of several high level simulation tools specialized in high frequency modelling, such as Grasp, ADS or HFSS, has been required. As a summary, this Master’s Thesis describes a real application of engineering, which includes coping with literature, designing according to specifications, simulating and performing experimental validation through measurements. Keywords Radar, space debris, W-Band, millimeter-wave, quasi-optical, Cassegrain, reflectarray, Gaussian beam, receiver, S-parameters, noise figure. Resumen Este Trabajo de Fin de M´aster expone el trabajo realizado en el marco del Proyecto SPADERADAR-CM, cuyo objetivo ´ultimoes el desarrollo de un radar de basura espacial embarcado que funcione a 94 GHz. Este tipo de radares tienen el prop´ositode detectar y realizar el seguimiento de peque˜nas part´ıculas de di´ametrosde 1 a 10 cm que orbitan alrededor de la Tierra a velocidades del orden de 15 km/s y que pueden ocasionar graves da˜nos en caso de colisi´on. En particular, este Trabajo de Fin de M´asterha contribuido al avance del Proyecto en diversos aspectos de la arquitectura hardware del sistema. Por una parte, se ha caracterizado el comportamiento lineal de la parte de milim´etricasdel subsistema receptor del radar. Por otra parte, se ha abordado el dise˜noy simulaci´on del sistema de antenas y se ha caracterizado el funcionamiento de un reflectarray que, en el futuro, podr´ıa incorporarse al radar para conseguir explorar el espacio mediante escaneo electr´onico. Aparte del estudio de la literatura existente sobre antenas y sistemas radar, la metodolog´ıa utilizada ha requerido la familiarizaci´on con equipos de medida para frecuencias milim´etricas. Adem´as, ha sido necesario el manejo de diferentes programas de simulaci´on especializados en el dise˜noy an´alisis en alta frecuencia, como son Grasp, ADS o HFSS. Por todo ello, el trabajo expuesto en esta memoria supone un trabajo de ingenier´ıa real, que incorpora investigaci´on,dise˜no,simulaciones y medidas experimentales, y que por tanto, lleva a la pr´actica muchos de los aspectos que han sido tratados en las asignaturas del M´asteren Teor´ıa de la Se˜nal y Comunicaciones. Palabras clave Radar, basura espacial, banda W, milim´etricas, cuasi-´optica, Cassegrain, reflectarray, haz gaussiano, receptor, par´ametros S, figura de ruido. Contents Abstract iii Keywords iii Table of contents vii List of Figures xi List of Tables xvii List of Acronyms xxi 1 Introduction and Objectives 1 1.1MotivationandContext................................ 1 1.2Objectives........................................ 1 1.3Methodology...................................... 2 1.4Structure........................................ 2 2 The Space Debris Radar 3 2.1TheSpaceDebrisProblem............................... 3 2.2SpaderadarSpecifications............................... 4 2.3SpaderadarArchitecture................................ 5 2.3.1 Basicarchitecture............................... 5 2.3.2 Noiseanddynamic-rangeconsiderations................... 6 2.3.3 Monopulseradar................................ 6 2.3.4 Antennasystem................................ 7 3 Antenna System Design 9 3.1TheSpaderadarAntennaSystem........................... 9 3.1.1 Cassegrainreflectorsystem.......................... 10 3.1.2 Monopulsefeed................................. 11 3.2DesignCriteria..................................... 11 vii viii CONTENTS 3.2.1 Restrictingdimensions............................. 12 3.2.2 Casestudies................................... 14 3.3AnalyticalSolution................................... 14 3.3.1 Analyticalequations.............................. 14 3.3.2 Analysisoftheresults............................. 15 3.4NumericalSolution................................... 16 3.4.1 Simulationset-up................................ 16 3.4.2 Simulationresultsofdifferentpre-designs.................. 17 3.4.3 Analysisoftheresults............................. 20 3.5FinalAntennaDesign................................. 21 3.5.1 Geometricaldefinition............................. 21 3.5.2 Simulationresults............................... 22 3.5.3 Considerationsonthefinalantennasystem................. 23 4 Simulation of Quasi-optical Measurement Systems 25 4.1TheoreticalBackgroundonQuasi-OpticalSystems................. 25 4.1.1 Gaussian beam propagation in free space .................. 25 4.1.2 Gaussianbeamtransformation........................ 27 4.2DevelopedGaussianBeamTracingTool....................... 30 4.2.1 Running the software ............................. 30 4.2.2 Step-by-step simulation process ........................ 30 4.2.3 Simulationresultsandoutputfiles...................... 31 4.2.4 Limitationsofthesimulationtool....................... 31 4.3 Application Example: 45◦ Incidence......................... 32 4.3.1 Designcriteria................................. 32 4.3.2 Simulatedopticalconfigurations....................... 33 4.3.3 Criticalanalysisofthesimulationresults.................. 33 5 Characterization of a W-band reflectarray 35 5.1TheoreticalBackgroundonReflectarrayAntennas................. 35 5.1.1 Reflectarrayantennasbasedonpatches................... 36 5.1.2 Reconfigurable reflectarrays based on liquid crystal ............. 36 5.2ReflectarraySampleUnderTest............................ 37 5.3Quasi-opticalTestBenches.............................. 38 5.3.1 Utilizedopticalcomponents.......................... 39 5.3.2 Optical set-up for 30◦ incidence........................ 39 5.3.3 Optical set-up for 45◦ incidence........................ 40 5.3.4 Comparison of lens-based and mirror-based set-ups for 45◦ incidence . 43 CONTENTS ix 5.4ReflectarrayCharacterization............................. 45 5.4.1 Measurementplan............................... 45 5.4.2 Statichomogeneouscontrol.......................... 46 5.4.3 Dynamiccontrolbasedontime-multiplexing................ 51 5.4.4 Discussionoftheresults............................ 54 5.4.5 Futuremeasurements............................. 56 6 Radar Receiving Chain Characterization. 57 6.1 The Millimeter-Wave Receiving Subsystem ..................... 57 6.2CharacterizationofIndividualComponents..................... 58 6.3 Characterization of the Receiver Isolation Chain .................. 59 6.3.1 Transmit insertion losses. ........................... 60 6.3.2 Isolationbetweenthetransmitterandthereceiver.............. 60 6.3.3 Power transfer from the antenna to the receiver. .............. 62 6.4 Noise Performance of the Receiver Chain ...................... 64 6.4.1 AnalyticalestimationusingFriisformula.................. 65 6.4.2 Noise budget analysis ............................. 67 6.4.3 Noisemeasurements.............................. 68 6.4.4 Conversion losses ................................ 70 6.5OverallConclusionsfromtheMeasurements..................... 71 6.5.1 Transmit-receive isolation ........................... 71 6.5.2 Maximumoutputpowerofthetransmitter................. 72 6.5.3 Receivernoisefloor............................... 72 6.5.4 Receiver sensitivity ............................... 73 7 Summary and Conclusions 75 7.1Summary........................................ 75 7.2Conclusions....................................... 75 A Simulations in Grasp 77 A.1POandPTD...................................... 77 A.2 Grasp configuration for simulating a Cassegrain system .............. 77 A.2.1Cassegrainantennamodel........................... 78 A.2.2Commandlist.................................. 78 B Optical Test Benches for 45◦ Incidence 81