OPTIMIZATION OF PULSE RADIATION FROM DIPOLE ARRAYS (TRANSIENT)
Abstract (Summary)The optimum solutions for pulse radiation from linear arrays of dipoles are derived in terms of the time-domain terminal voltages for two cases: (1) the maximum electric field at a specified far-field position and time and (2) the maximum energy density in a specified time duration at a specified far-field position. For field maximization, an array of independently fed dipoles, and an array of dipoles fed by a single voltage waveform with time-delays between the dipole terminals are investigated. The optimum time-delays for the arrays fed by a single voltage waveform are found by a numerical search technique. For energy maximization, arrays of independently fed dipoles are investigated. For all cases, input signal voltages are constrained to have a finite energy and finite frequency bandwidth with the dipole currents restricted by the Pocklington integral equation. The integral equation is solved at each discretized frequency in the specified bandwidth by the method of moments with piecewise sinusoidal modes and a Galerkin procedure. Optimizations are performed to derive the frequency-domain solutions and then the time domain waveforms are found by Fourier inversion. Optimization with an additional constraint on the radiation patterns is also presented. As an example, the problem of a sidelobe level constraint applied to the above field maximization and energy maximization problem is treated. The optimum solution procedure is modified such that the sidelobe level at each discrete frequency in the band of interest is equal to a specified level. In carrying out the optimization with a sidelobe constraint, compensation is made for the pattern error caused by mutual coupling effects. This correction is not already included in the optimization procedure because the procedure uses the CW synthesis technique that is valid only for elements without mutual coupling. The peak field intensity obtained with the field-maximization procedure forms an upper bound to that obtained using energy maximization. The use of the Singularity Expansion Method (SEM) for optimum pulse radiation from dipole arrays is also discussed.
School Location:USA - Massachusetts
Source Type:Master's Thesis
Date of Publication:01/01/1986