Master of Science in Engineering, University of Akron, 2018, Electrical Engineering

This thesis discusses a detailed study of the design and performance analysis of patch antenna arrays at different frequencies. A linear hybrid array of 16 elements is built using patch antennas integrated with an RF front-end using commercial off-the-shelf (COTS) components. A well organized receiver chain that can work at a frequency in the range of 5 - 6 GHz is built using chip level components on a printed circuit board (PCB). This study mainly emphasizes the design and implementation of the comprehensive receiver beamforming systems using fast Fourier transform (FFT) algorithm and approximate - discrete Fourier transform (a-DFT). A low complexity 32-beam multi-beamformer at 5.8 GHz is designed, built and implemented in real time using optimized digital FPGA cores as the digital back-end which is collaborated work with Viduneth Ariyarathna. The emanating beams were measured and verified using the FPGA - based 32-element 5.8 GHz array setup which can generate 120 MHz bandwidth per channel. The beams corresponding to the approximate DFT are in good agreement with the beams corresponding to the FFT with negligible error approximately less than -14 dB. This setup can be used as a test bed to measure and evaluate various signal processing algorithms up to 32 linear array elements.

Committee: Arjuna Madanayake Dr (Advisor); Nghi Tran Dr (Committee Member); Ryan Christopher Toonen Dr (Committee Member) Subjects: Computer Engineering; Electrical Engineering

Master of Science in Engineering, University of Akron, 2017, Electrical Engineering

During the past few decades, considerable research has been carried out on beamforming and its techniques. Applications of beamforming include areas such as wireless communications, cognitive radio, and cooperative wireless sensor networks. These applications require highly directional and electronically scanned smart antenna arrays that are capable of filtering real-time broadband plane waves at radio frequencies (RFs). In this thesis, a low-complexity reliably fast second order two-dimensional (2D) infinite impulse response (IIR) spatially-bandpass (SBP) beam filter is designed, implemented and verified. An extensive study on theory and simulations of the filter has been done in the past, but real world implementation of this filter was not previously attempted. This study mainly focuses on building comprehensive beamforming systems. A linear 16-element beamforming receiver is constructed using micro-strip patch antennas and integrating it with a radio-frequency front-end built using commercial off the shelf components (COTS). The exact design specifications of all the microwave and digital circuits have been derived and presented. The antenna array design is simulated, and its far-field radiation properties and S-parameters are plotted. The measurements from the constructed array are also included and are compared with the simulation results. The output from the RF receiver chain is digitized and given to the digital 2D filter that is implemented on ROACH-2 FPGA platform. The filter architecture is designed such that the beam can be software controlled using developed python scripts, thus making the testing of the filter user-friendly. The construction of a radio-frequency anechoic chamber is explained, where the entire experimental setup can be used for testing for confirming the correctness of the proposed filter. As an additional part of this research work, a 4 x 4 digital beamforming receiver for detecting UASs is designed and fabricated ; it can be u (open full item for complete abstract)

Committee: Arjuna Madanayake Dr (Advisor); Nghi Tran Dr (Advisor); Kye-Shin Lee Dr (Committee Member); Joan Carletta Dr (Committee Chair) Subjects: Computer Engineering; Electrical Engineering; Engineering

Master of Science in Engineering (MSEgr), Wright State University, 2010, Electrical Engineering

Digital microwave receivers play a critical role in many of today's modern radar tracking systems. The need for these digital receivers to push the boundaries in terms of bandwidth and input dynamic ranges (DR) is vital for their use in radar signal tracking. Significant research has been conducted in the area of the fast Fourier transform (FFT) to aid in continuing to enhance the performance capabilities of digital microwave receivers. However, with the advancement and increased complexity of these systems, the need for an efficient and effective adaptive thresholding technique is becoming ever more present. The proposed adaptive thresholding technique utilizes signal magnitude evaluations and multi-stage signal scaling throughout a 128-point FFT in order to effectively determine the optimal threshold for the microwave receiver. The incorporation of a 10-bit dynamic kernel function, as well as 14-bit word size between FFT stages is used to aid in increasing receiver sensitivity, multi-tone instantaneous dynamic range (IDR) and spurious free dynamic range (SFDR) performance. With the implementation of our adaptive thresholding technique, our receiver's maximum IDR is maintained between 34dB down to 24dB for input signal strengths ranging from -4dBm down to -32dBm. From simulation results incorporating the use of digitized data from our 10-bit Atmel ADC our Multi-Stage Scaling (MSS) receiver design is capable of obtaining an SFDR of 35.91dB using an input signal strength of -7dBm.

Committee: Henry Chien-In PhD (Advisor); Marian Kazimierczuk PhD (Committee Member); Saiyu Ren PhD (Committee Member) Subjects: Electrical Engineering

Master of Science in Engineering (MSEgr), Wright State University, 2006, Electrical Engineering

General purpose receivers of today are designed with a broad bandwidth so that the receiver can accept a wide range of signal frequencies. These receivers usually accept one signal along with any interference that is included. To increase the signal detection capabilities of the wideband receiver, a design for a receiver that can detect two signals is needed. One of the requirements for this receiver is that the second weak signal needs to be processed in a timely manner so that the receiver can recognize it. To remedy the problem, a module was developed using wavelet-based techniques to remove spurs from the incoming signals to allow easier detection. The main basis for this concentration on wavelets comes from the way wavelets break down signals into portions (called resolutions) that allow easier determination of detail importance. Utilizing the multi-resolution attributes of the discrete wavelet transform, a way to remove signal spurs is made possible. When removing the signal noise from the signal, the two signal dynamic range of the system is increased, as this module is applied to multiple receiver systems for comparison of performance. Implementation of this system was originally done in C as well as MATLAB, but later is being implemented in VHDL with simulations done for verification of functionality.

Committee: Chien-In Henry Chen (Advisor) Subjects: