Recent developments in the field of phased array feeds for radio astronomical reflector antennas, have opened a new frontier for array signal processing for radio astronomy observations. The goal is to replace single horn feeds with a phased array feed, so as to enable astronomers to cover more sky area in less time. The development of digital backend signal processing systems has been a major area of concentration for the development of science-ready phased array feeds for radio astronomers. This thesis focuses on the development of analog down-converter receivers and an FPGA-based digital backend for real-time data processing and analysis support for phased array feeds. Experiments were conducted with new receiver boards and both single-polarization and dual-polarization phased array feeds at the Arecibo Observatory, Puerto Rico and at the 20-meter telescope at Green Bank, WV, and results were analyzed. The experiments were performed as a part of a feasibility study for phased array feeds. The new receiver boards were developed as an upgrade to the earlier connectorized receivers as the number of input channels increased from 19 to 38 and space constraints arose due to the large size of the earlier receivers. Each receiver card has four independent channels on it. The receiver cards were found to have lower cross-coupling between the channels in comparison to the earlier receivers. The development of a FPGA-based real time digital backend focused on a real-time spectrometer, beamformer and a correlator for all the 64-channels using a x64 ADC card and ROACH FPGA boards. The backend can plot results in real time and can stream and store the data on the computers for purpose of post-processing and data analysis. The design process uses libraries and blocks provided by the Center for Astronomy Signal Processing and Electronics Research (CASPER) community.

This dissertation explores the expansion of the Electrically Steerable Parasitic Array Radiator (ESPAR) technology to arrays using microstrip patch elements. Scanning arrays of two and three closely-coupled rectangular patch elements are presented, which incorporate no phase shifters. These arrays achieve directive radiation patterns and scanning of up to 26° with maintained impedance match. The scanning is effected by tunable reactive loads which are used to control the mutual coupling between the elements, as well as additional loads which compensate to maintain the appropriate resonant frequency. The design incorporates theoretical analysis of the system of coupled antennas with full-wave simulation. A prototype of the threeelement array at 1 GHz is fabricated and measured to exhibit a maximum gain of 7.4 dBi with an efficiency of 79.1%. Further, the microstrip ESPAR is thoroughly compared to uniformlyilluminated arrays of similar size. To satisfy the need for higher directivity antennas with inexpensive electronic scanning, the microstrip ESPAR is then integrated as a subarray. The three-element subcell fabrication is simplified to a single layer with an inverted-Y groove in the ground plane, allowing for DC biasing without the need for the radial biasing stubs or tuning stubs found in the two-layer design. The 1 GHz ESPAR array employs a corporate feed network consisting of a Wilkinson power divider with switchable delay line phase shifts, ring hybrid couplers, and achieves a gain of 12.1 dBi at boresight with ±20° scanning and low side lobes. This array successfully illustrates the cost savings associated with ESPAR subarray scanning and the associated reduction in required number of phase shifters in the RF front end.

Reflectarrays are passive quasi-periodic sub-wavelength antenna arrays designed for discrete reflected phase manipulation at each individual antenna element making up the array. By spatially varying the phase response of the antenna array, reflectarrays allow a planar surface to impress a non-planar phasefront upon re-radiation. Such devices have become commonplace at radio frequencies. In this dissertation, they are demonstrated in the infrared for the first time--at frequencies as high as 194 THz. Relevant aspects of computational electromagnetic modeling are explored, to yield design procedures optimized for these high frequencies. Modeling is also utilized to demonstrate the phase response of a generalized metallic patch resonator in terms of its dependence on element dimensions, surrounding materials, angle of incidence, and frequency. The impact of realistic dispersion of the real and imaginary parts of the metallic permittivity on the magnitude and bandwidth of the resonance behavior is thoroughly investigated. Several single-phase reflectarrays are fabricated and measurement techniques are developed for evaluating these surfaces. In all of these cases, there is excellent agreement between the computational model results and the measured device characteristics. With accurate modeling and measurement, it is possible to proceed to explore some specific device architectures appropriate for focusing reflectarrays, including binary-phase and phase-incremental approaches. Image quality aspects of these focusing reflectarrays are considered from geometrical and chromatic-aberration perspectives. The dissertation concludes by briefly considering two additional analogous devices--the transmitarray for tailoring transmissive phase response, and the emitarray for angular control of thermally emitted radiation.

Radio frequency interference (RFI) is undesired and commonplace. Using a subspace projection method to spatially remove the interference from a phased array system gives results of a 30 dB interference null rejection (INR). Unmanned systems have been developed to observe underwater activity and communicate their observations to passing aircraft. These systems are currently limited by their use of a single transmitter. The uplink can be improved by using a dual-antenna beam steering approach to maximize the signal-to-noise ratio (SNR) the aircraft receives. This approach demonstrates an increase in SNR of 3 dB when compared to a single transmitter.

Yes / In this manuscript, a high-performance beam-steerable phased array antenna is introduced for fifth-generation (5G) mobile handsets. The configuration of the design is arranged by employing eight dielectric-insensitive L-ring/slot-loop radiators in a linear form on the top edge of the handset mainboard. The beam-steerable array design exhibits high radiation performances even though it is implemented on a lossy FR-4 material. The proposed design exhibits an impedance bandwidth of 18-20 GHz with the center frequency of 19 GHz. It provides satisfactory characteristics such as wide beam-steering, high gain and efficiency characteristics indicating its promising potential for beam-steerable 5G smartphones. The characteristics of the antenna array are insensitive for different types of dielectrics. Furthermore, the designed antenna array offers quite good radiation behavior in the presence of hand phantom.

The Electronically Steered Phased Array is one of the most versatile antennas used in radars applications. Some of the advantages of electronic steering are faster scan, no moving parts and higher reliability. However, the cost of phased arrays has always been prohibitive - in the order of $1M per square meter. The cost of a phased array is largely impacted by the cost of the high frequency electronics at each element and the cost of packaging. Advances in IC integration will allow incorporating multiple elements such as low noise amplifier, power amplifier, phase shifters and up/down-conversion into one or two ICs. Even though the cost for large quantities of ICs (both Silicon and GaAs) has lowered, the high cost of IC packaging and the array backplane still make the use of phase arrays for radar applications costly. The focus of this research is on techniques that reduce the packaging and the backplane cost of large electronically steered arrays. These techniques are based on simplified signal distributions schemes, reduction of layers in the backplane and use of inexpensive materials. Two architectures designed based on these techniques, as well as a novel BGA active antenna package for dual polarized phased arrays are presented. The first architecture, called the series fed row-column architecture, focuses on the reduction of phase shifters and control signals used in the backplane of the array. The second architecture, called the parallel plate feed architecture, is based on a simplified scheme for distribution of the local oscillator signal. A prototype making use of each one of these architectures is presented. Analysis of advantages and disadvantages of each of these architectures is described. The necessity of cost reduction is a factor that can possibly impact the polarization performance of the antenna. This factor is a motivation to study and develop calibration techniques that reduce the cross-polarization of electronically steered phased arrays. Advances on Interleaving Sparse Arrays, a beam forming technique for polarization improvement/correction in phased arrays, are also presented.

RF receiver improvements in size, weight, power, and sensitivity are constant goals in the wireless communications community. The combination of phased array antenna systems with high speed analog to digital converters helps engineers meet these goals, because many of the analog components and tasks found in a traditional receive chain are moved into the digital domain. Although the hard work of signal reception is moved into digital signal processing, digital receivers rely on a high performance analog front end to properly condition a signal before analog to digital conversion. In this thesis, two RF front ends are developed for direct sampling L-band phased array receiver applications, which comprise the two main chapters of this document. Both RF front ends are developed on low cost, quick turnaround time PCB materials. Results for system gain and noise figure are presented for each front end. First, the development of an L-band analog front end for a direct sampling GPS phased array receiver is described, with particular attention to gain and noise figure in context of the full system link budget. The RF front end for the GPS phased array receiver meets design expectations by achieving a system gain of 65 dB and a system noise figure of 1.5 dB at the GPS L1 frequency. Second, the redesign and improvement of the Advanced L-band Phased Array Camera (ALPACA) RF over fiber transmitter is documented. New mechanical and electrical design requirements were brought on from the change of target observatory from the collapsed Arecibo obervatory in Puerto Rico, to the Greenbank Observatory in Greenbank, West Virginia. The ALPACA RF over fiber signal transport system with the redesigned transmitter reaches the design expectation of a system noise temperature contribution less than 1 K. Average gain of the RF over fiber system is 49 dB, gain differences between channels are less than 2 dB, and isolation between channels is better than 35 dB. Under optimal conditions, the noise figure of the RF over fiber link is 2.4 dB (213.3 K), which allows for up to 11 dB of attenuation to be added to any given transmit channel to level the gain across all 138 ALPACA channels.

With the expansion of unmanned aircraft system (UAS) technologies, there is a growing need for UAS Traffic Management (UTM) systems to promote safe operation and development. To be successful, these UTM systems must be able to detect and track multiple drones in the presence of clutter. This paper examines the implementation of different algorithms on a compact, X-band, frequency modulated continuous wave (FMCW) radar in an effort to enable more accurate detection and estimation of drones. Several algorithms were tested through post processing on actual radar data to determine their accuracy and usefulness for this system. A promising result was achieved through the application of pulse-Doppler processing. Post processing on recorded radar data showed that a moving target indicator successfully separated a target from clutter. An improvement was also noted for the implementation of phase comparison monopulse which accurately estimated angle of arrival (AOA) and required fewer computations than digital beamforming.The second part of this thesis explains the work done on an adaptive broadband, real time beamformer for RF interference (RFI) mitigation. An effective communication system is reliable and can counteract the effects of jamming. Beamforming is an appropriate solution to RFI. To assist in this process FPGA firmware was developed to prepare signals for frequency domain beamforming. This system allows beamforming to be applied to 150 MHz of bandwidth. Future implementation will allow for signal reconstruction after beamforming and demodulation of a communication signal.

Denna avhandling går ut på att undersöka verkningsgradens temperaturberoende för SHG (second harmonic generation) från 1030nm till 515nm, i en kvasifasmatchad KTP-kristall, för både pulsad och CW (continuous wave)-laser. Detta undersöktes då det har tidigare noteras att verkningsgraden hos en KTP-kristall avtar när effekten på lasern ökar. Det är på grund av ökad värmeutveckling från absorption (se Figur 1). I denna rapport undersöktes detta genom att variera lasereffekten, kyla KTP-kristallen med en temperaturgradient och mäta dess effekter på verkningsgraden. För att undersöka fallet med CW skapades ett simuleringsprogram i Python, då det inte fanns en tillräckligt stark CW-laser tillgänglig. En laser med femtosekundspulser användes för att mäta verkningsgraden för pulsad laser. Resultaten visade att CW-lasern som förväntat var känslig för temperaturförändringar och att det orsakade att verkningsgraden minskade med effekten. Dessutom visade simuleringen att en temperaturgradient var ett effektivt sätt att höja verkningsgraden om den applicerades korrekt. Den pulsade lasern uppvisade ett annat beteende. Den var mycket stabil för stora temperaturspan, 7% skiljde mellan högsta och lägst effekt på ett temperaturspan på 70°C.

This thesis develops and presents a new remanufacturing MRP time-phased scheduling algorithm utilizing a critical path concept, as in the project management field, for incorporation into remanufacturing production planning MRP calculations. The algorithm automates the remanufacturing lead time allowance calculation for child subassemblies and component parts in the form of Stack Time, and as such creates a linkage between the parent remanufacturing routing operation to which a remanufactured subassembly or component part is allocated for further processing, and the parent routing operation from which it is disassembled. This new MRP scheduling algorithm is optimal for calculating the total planned production time of remanufacturing production routings, and is appropriate for even large, complex, multilevel BOM structures.