Type of Document	Dissertation
Author	Connor, Jeffrey David
Author's Email Address	jdconnor23@hotmail.com
URN	etd-07082008-200534
Title	Antenna Array Synthesis Using the Cross Entropy Method
Degree	Doctor of Philosophy
Department	Electrical and Computer Engineering, Department of
Advisory Committee	Advisor Name Title Simon Foo Committee Chair Mark Weatherspoon Committee Co-Chair Amy Chan-Hilton Committee Member Anke Meyer-Baese Committee Member
Keywords	Half Power Beamwidth Beamwidth First Null Beamwidth Beam Efficiency Null Location Null Null Position Probability Distribution Gaussian Distribution Normal Distribution Bernoulli Distribution Variance Injection Method Accelerated Cross Entropy Method Sidelobe Power Shaping Null Depth Importance Sampling Particle Swarm Optimization Simulated Annealing Fully Adaptive Cross Entropy Method Online Cross Entropy Method Multi-Objective Cross Entropy Method Thinning Periodic Array Sector Beam Pencil Beam Element Spacings Grating Lobe Grating Lobe Suppression Null Placement Symmetric Array Factor Uniform Linear Array Chebyshev Array Taylor Array Array Failure Correction Non-Dominated Solution Pareto Front Pareto Optimal Solution Array Design Statistical Array Thinning Antenna Array Synthesis Nature Inspired Metaheuristic Genetic Algorithm Statistical Element Thinning Antenna Array Design Antenna Array Cross Entropy Method Evolutionary Algorithm Cognitive Intelligence Combinatorial Optimization Continuous Optimization Stochastic Optimization Multi-Objective Optimization Optimization Non-Uniform Element Spacings Element Thinning Array Thinning Phased Array Design Phased Array Aperiodic Array Design Aperiodic Array Linear Array Array Factor Field Pattern Radiation Pattern Power Pattern Lo's Bound Steinberg Bound Peak Sidelobe Level Peak Sidelobe Power Sidelobe Level Sidelobe Sidelobe Power Mainlobe Shaped Beam Pattern Harmony Search Tabu Search Taguchi's Method Bees Algorithm Ant Colony Optimization Electromagnetic Optimization Phase-Only Array Design Switched Beam Design Matlab Complex Array Weight Design Amplitude-Only Array Design
Date of Defense	2008-06-19
Availability	unrestricted
Abstract This dissertation addresses the synthesis of antenna arrays using the Cross-Entropy (CE) method, marking the first application of the CE method for solving electromagnetic optimization problems. The CE method is a general stochastic optimization technique for solving both continuous and discrete multi-extremal, multi-objective optimization problems. The CE method is an adaptive importance sampling derived from an associated stochastic problem (ASP) for estimating the probability of a rare-event occurrence. The estimation of this probability is determined using a log-likelihood estimator governed by a parameterized probability distribution. The CE method adaptively estimates the parameters of the probability distribution to produce a random variable solution in the neighborhood of the globally best outcome by minimizing cross entropy. In this work, single and multi-objective optimization using both continuous and combinatorial forms of the CE method are performed to shape the sidelobe power, mainlobe beamwidth, null depths and locations as well as number of active elements of linear array antennas by controlling the spacings and complex array excitations of each element in the array. Specifically, aperiodic arrays are designed through both non-uniform element spacings and thinning active array elements, while phased array antennas are designed by controlling the complex excitation applied to each element of the array. The performance of the CE method is demonstrated by considering different scenarios adopted from literature addressing more popular stochastic optimization techniques such as the Genetic Algorithm (GA) or Particle Swarm Optimization. The primary technical contributions of this dissertation are the simulation results computed using the Cross Entropy method for the different scenarios adopted from literature. Cursory comparisons are made to the results from the literature, but the overall goal of this work is to expose the tendencies of the Cross Entropy method for array synthesis problems and help the reader to make an educated decision when considering the Cross Entropy method for their own problems. Overall, the CE method is a competitive alternative to these more popular techniques, possessing attractive convergence properties, but requiring larger population sizes.
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