Embedded below the radome of a missile, existing RF-seekers use a mechanical rotating antenna to steer the radiating beam in the direction of a target. Latest research is looking at replacing the mechanical antenna components of the RF seeker with a novel 3D conformal antenna array that can steer the beam electronically. 3D antennas may oer signicant advantages, such as faster beamsteering and better coverage but, at the same time, introduce new challenges resulting from a much more complex radiation pattern than that of 2D antennas. Thanks to the mechanical system removal, the new RF-seeker has a wider available space for the design of a new 3D conformal antenna. To take best benets of this space, dierent array shapes are studied, hence the impact of the position, orientation and conformation of the elements is assessed on the antenna performance in terms of directivity, ellipticity and polarisation. To facilitate this study of 3D conformal arrays, a Matlab program has been developed to compute the polarisation pattern of a given array in all directions. One of the task of the RF-seeker consists in estimating the position of a given target to correct the missile trajectory accordingly. Thus, the impact of the array shape on the error between the measured direction of arrival of the target echo and its true value is addressed. The Cramer-Rao lower bound is used to evaluate the theoretical minimum error. The model assumes that each element receives independently and allows therefore to analyse the potential of active 3D conformal arrays. Finally, the phase monopulse estimator is studied for 3D conformal arrays whose quadrants do not have the same characteristics. A new estimator more adapted to non-identical quadrants is also proposed.

Modern satellite, wireless communication, and radar systems often demand wideband performance for multi-channel operation and the ability to steer multiple beams for multiple moving targets. This dissertation covers a variety of topics to design low-cost and wideband antenna systems. The main areas of study are microwave devices controlled piezoelectric transducers (PETs) and wideband baluns and balanced microwave circuits using parallel-strip lines. Some focus has also been given to the design of Rotman lens for multiple beam generation and Vivaldi antenna arrays for wideband two-dimensional scanning. The dielectric perturbation technique controlled by PET is introduced to design a wideband phase shifter and a QPSK modulator, and to tune the resonant frequency of a slot dipole. The designed PET-controlled phase shifters are used for beam steering in a dual beam phased array using a bidirectional feeding scheme and a five-beam phased array using a microstrip Rotman lens. Vivaldi-type antennas are commonly used to achieve wideband performance. Very wideband performance can be achieved using an antipodal tapered slot antenna because of its inherent simple wideband transition from microstrip line to parallel-strip line. An antipodal tapered slot antenna and a phased array are designed to span 10 to 35 GHz. In addition, a 4??4 two-dimensional antenna array is designed using wideband antipodal tapered slot antennas, and two sets of PET-controlled phase shifters for E- and H-plane scanning are fabricated to steer the beam. As a microwave system using wideband antenna array, a new low-cost and wideband phased array radar is developed using a modulated pulse over 8 to 20 GHz band. The double-sided parallel-strip line as a balanced line is presented. The parallelstrip line offers much flexibility for microwave circuit designs. This transmission line makes it possible to realize a low impedance line and allows the design of a compact wideband balun and junction. Wideband transitions (or baluns) from parallel-strip line to microstrip line, a typical unbalanced transmission line, are realized to cover several octave bandwidth. Balanced microwave filters and a hybrid coupler are developed using the parallel-strip line.

This thesis describes the investigation of photonic crystals as a substrate in microstrip phased array antennas. Alumina with a relative dielectric constant of 9.6 is used as substrate to obtain miniaturization of the components in the high-frequency range. The proposed design consists of four rectangular patches in a linear array conguration operating at 12 GHz. The antenna elements are excited by a microstrip feed line using the inset feeding technique for perfect impedance matching. A beam steering of 20o is achieved using a switched line phase shifter. Antenna parameters, including impedance matching, bandwidth, gain, directivity and the S parameters of the proposed array antenna are obtained. The simulation results are obtained with the Advanced Design System (ADS) simulator.

"Theoretical modeling, design, assembly, and measurement of a novel integrated phased array radiator are presented. The droopy bowtie turnstile radiator with quad line feed meets challenging radar requirements and uses low cost manufacturing and assembly techniques. This thesis develops the complete theoretical model (antenna, balun, feeding network) of a broadband phased array radiator: the droopy bowtie turnstile radiator. A novel quad line balun feed is developed that provides a low loss, high isolation, and coincident phase-center feeding network for the droopy bowtie. The radiator and feed design combines broadband RF performance and high-isolation dual-linear polarization in a low profile, compact package that enables wide scan volume performance versus frequency. This thesis develops low-cost manufacturing and assembly techniques applied to the droopy bowtie radiator with the quad line feed. The new radiator design would utilize low cost fabrication techniques such as injection molding and 3-D printing, and also leverages automated assembly techniques. Measurement prototypes and array prototypes of droopy bowtie radiators with the quad line feed are developed for L- and X-bands. The measurements demonstrate broadband RF performance in a low profile compact package viable for wide-scale phased array applications."

Cognitive radio networks require the use of computational resources to reconfigure transmit/receive parameters to improve communication quality of service or efficiency. Recent emergence of smart phones has made these resources more accessible and mobile, combining sensors, geolocation, memory and processing power into a single device. Thus, this work examines an integration of a smart phone into a complex radio network that controls the beam direction of a phased array using a conventional method, but utilizes the phone's internal sensors as an enhancement to generate beam direction information, Bluetooth channel to relay information to control circuitry, and Global Position System (GPS) to track an object in motion. The research and experiments clearly demonstrate smart phone's ability to utilize internal sensors to generate information used to control beam direction from a phased array. Computational algorithms in a network of microcontrollers map this information into a DC bias voltage which is applied to individual phase shifters connected to individual array elements. To test algorithms and control theory, a 4 by 4 microstrip patch array is designed and fabricated to operate at a frequency of 2.4 GHz. Simulations and tests of the array provide successful antenna design results with satisfactory design parameters. Smart phone control circuitry is designed and tested with the array. Anechoic test results yield successful beam steering capability scanning 90 degrees at 15 degree intervals with 98% accuracy in all cases. In addition, the system achieves successful beam steering operable over a bandwidth of 100 MHz around resonance. Furthermore, these results demonstarate the capability of the smart phone controlled system to be used in testing further array formations to achieve beam steering in 3-Dimensional space. It is further noted that the system extends capabilities of integrating other control methods which use the smart phone to process information.

International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / Conventional phased arrays nominally sum the signals received by the elements prior to detection. By multiplying rather than summing signals received from pairs of elements, i.e., interferometer pairs, a set of Spatial Frequencies (SFs) is obtained. Obtaining the SFs requires employment of a multiple local oscillator technique. When summed, these spatial frequencies produce a single lobed (voltage) radiation pattern which, when passed through a biased detector, removes all sidelobes from the response at a small loss of desired signal power.

Over the past decades, phased arrays have played a significant role in the development of modern radar and communication systems. The availability of printed circuit technology and ease of integration with microwave components, as well as the development of low profile and low weight approaches, have also played an important role in their conformal adaptation. However, fabrication costs remain prohibitive for many emergent platforms, including 5G base stations and autonomous vehicles, when compared to a conventional mechanically steered passive array. Therefore, cost reductions in the fabrication and integration of modern phased arrays are essential to their adaptation for many upcoming commercial applications. Indeed, although phased array design methods are well-understood, even for wideband and wide-angle scanning applications, their fabrication is still based on high-cost, low-yield printed circuit technology. With this in mind, this dissertation focuses on a new planar aperture topology and low-cost techniques for phased array methodologies. The first part of the thesis presents new fabrication advancements using commercially available multi-layered printed circuit technologies. We discuss methods for low cost fabrication while still maintaining performance and design constraints for planar array apertures. The second part of the dissertation presents a novel Integrated Planar Array (IPA) at S-Band and discusses dramatic cost reductions for multi-function radar applications. Performance and cost benefits are presented, and fabrication techniques to exploit an emerging class of high-speed digital laminates are discussed. These are compatible with high-volume, high-yield production, while reducing aperture cost by 75% when compared to conventional approaches. Performance of a planar array employing a pin-fed dual-polarized antenna element with active VSWR Overall, this dissertation addresses several manufacturing and performance challenges in realizing affordable planar phased arrays using low cost fabrication without performance compromise. As commercial interest in phased array technology is anticipated to grow, the proposed approaches for phased array design and fabrication will enable quick turnaround times for mainstream adoption.

In today’s technologically driven world, antennas play an essential role in enabling wireless communications over long distances and allow communities to interact on a global scale. Typically, this is done using large networks of antenna systems on the ground and in space to ensure signals reliably arrive at their destinations, which can be very expensive in terms of replacement cost and maintenance as the number of nodes increase. We shall be discussing a new method for deploying space-borne antennas via CubeSats that will enable high speed communications with the ground and other satellites at a fraction of the cost and complexity of traditional communication systems. Specifically, the focus will be on the design of a phased array line feed and the backend systems for a CubeSat deployable inflatable spherical reflector that is electronically steerable to any direction in azimuth and elevation.

Ingeniero Civil Eléctrico / La síntesis de haces resuelve el problema de generar patrones de radiación más complejos que los que se puede generar con antenas individuales o arreglos de estas. Para ello se manipula la fase y la amplitud de la alimentación de cada elemento del arreglo, lo que permite focalizar la emisión o recepción de la potencia en ciertos lugares del espacio. Tanto en radioastronomía, como en las telecomunicaciones, esta tecnología da la posibilidad de observar el espacio de manera selectiva y/o en múltiples direcciones de manera simultanea, lo cual permite disminuir tiempos de barrido (para el caso de radiotelescopios) o descongestionar canales creando enlaces directivos. Este trabajo presenta la implementación de un sintetizador digital de múltiples haces, utilizando un arreglo planar de de 4x4 antenas tipo parche, capaz de generar tres patrones patrones directivos, cuyo procesamiento se realiza íntegramente en una FPGA (Field Programmable Gate Array). El arreglo está sintonizado para operar en 5.81 GHz, con un ancho de banda de 40 MHz. La señal es convertida a banda base por un conjunto de tarjetas de electrónica analógica. Se han realizado dos pruebas experimentales para verificar el funcionamiento del sistema: una emulando condiciones ideales de excitación, de modo de eliminar interferencias ajenas al experimento, y otra situando el arreglo en un extremo de una habitación vacía, siendo iluminado por una fuente puntual en el otro extremo. Los resultados permiten concluir que la síntesis de haces es satisfactoria, generando haces cuyo lóbulo principal es de 20º de ancho, con la capacidad rotar la dirección en que apuntan en todo el hemisferio visible del arreglo.

Over the years, phased array antennas have provided electronic scanning with high gain and low sidelobe levels for many radar and satellite applications. The need for higher bandwidth as well as greater scanning ability has led to research in the area of aperiodically spaced antenna arrays. Aperiodic arrays use variable spacing between antenna elements and generally require fewer elements than periodically spaced arrays to achieve similar far field pattern performance. This reduction in elements allows the array to be built at much lower cost than traditional phased arrays. This thesis introduces the concept of aperiodic phased arrays and their design via optimization algorithms, specifically Particle Swarm Optimization. An axial mode helix is designed as the antenna array element to obtain the required half power beamwidth and bandwidth. The final optimized aperiodic array is compared to a traditional periodic array and conclusions are made. / Master of Science