Edward B. Joy’s research while affiliated with Georgia Institute of Technology and other places

A practical technique is developed to determine the electric and/or magnetic field on objects and sources inside a spherical measurement surface. The technique, known as spherical microwave holography (SMH), provides a nondestructive, nonintrusive method of point-by-point evaluation of antennas and radomes over their spatial extent. The resolution capability of SMH is developed and demonstrated by measurements. Resolution in SMH is only limited by the measurement system's capabilities. Dielectric and metallic obstacles on the surface of a radome are located and identified. Resolution as small as 0.33λ₀ is demonstrated

Test zone field (TZF) compensation increases antenna pattern measurement accuracy by compensating for extraneous fields created by reflection and scattering of the range antenna field from fixed objects in the range and by leakage of the range RF system from a fixed location in the range. TZF compensation can be used on fixed line-of-sight (static) far-field, compact, and near-field ranges. Other compensation techniques are seldom used in practical measurement situations because they are limited in the amount of compensation they provide. These techniques do not adequately model the type of extraneous field present in the range or require increased measurement time and equipment necessary to implement the technique. TZF compensation overcomes these limits as follows. The TZF is measured over a spherical surface encompassing the test zone using a low gain probe. The measured TZF is used antenna pattern measurements to compensate for extraneous fields. TZF compensation theory is presented and demonstrated using measured data

A methodology that is a combination of analysis, computer simulation, component certification, self-tests, and comparison tests is presented for the accuracy qualification of near-field antenna measurement ranges. The analysis uses closed-form equations to establish upper-bound far-field determination errors due to near-field measurement errors. Computer simulation is used to model the specific near-field measurement errors associated with the near-field measurement system components. The closed-form equations and computer simulations are used to form a near-field error budget for each of the near-field measurement system components. A near-field system component certification is undertaken to measure the near-field measurement system component error and establish that they are within the error budget

The activity of the Georgia Institute of Technology in the development of the near-field measurement technique is reviewed. The work conducted during the years 1967-73 is given primary importance, and the major near-field developments in the 1973-80 time period are also described

This paper presents the results of a study conducted to assess the accuracy of a widely used computer algorithm for the analysis of grounding grids. The paper concludes with recommended practices for both horizontal and vertical grid conductor segmentation for the calculation of resistance and earth surface voltages for simple structures.

This paper presents recent developmental advances for the computation of maximum ground potential rise of grounding structures or alternatively maximum earth current in substation grounding systems. An advanced methodology for short circuit analysis is presented. The methodology is based on modeling of power system elements in direct phase quantities. Coupled with equivalency techniques, it provides an extremely efficient algorithm for performing numerous sequential short circuit analyses. An easy to use computer program has been developed under EPRI sponsorship. The computer algorithm uses the methodology to search for the fault condition which yields the maximum earth current in a substation grounding system. The methodology has been validated with actual system measurement on a Georgia Power Company Substation. Validation results are presented. Typical results as well as program utilization factors are discussed. The results demonstrate that the worst fault location is highly dependent on system parameters and cannot be predicted with simple rules.

The paper presents graphical data for the calculation of ground grid resistance, corner mesh potential and corner step potential for a restricted class of ground grids. The restricted class of ground grids are similar to those considered in the IEEE Guide for Safety In Substation Grounding, IEEE Standard 80-1976, where the primary restrictions are uniform soil, rectangular grid shape, and uniform conductor spacing. The data presented represents the computer analysis of over 2,385 ground grid configurations using the method of moments (also called a finite element analysis) computer algorithm GRID developed at Georgia Tech under EPRI sponsorship. This computer algorithm has been validated with several field measurement programs. The graphical data is for square grids with square meshes. Simple equations are presented to extend this data to rectangular grids with rectangular meshes.

A method for computing shield potentials of underground directly buried (URD) cable is presented. Earth potentials in the vicinity of the buried cable are also computed. The method utilizes a numerical solution of Laplace's equation to account for earth currents, and a modified nodal analysis method to account for conductor and shield currents as well as inductive coupling in the underground cable system. A computer program has been developed capable of analyzing long lengths of URD cable together with existing ground rods, faults, open neutrals, feeding substation and substation grounds. The system analyzed corresponds to practical URD cable distribution systems. Extensive simulation of various URD cable systems in various soil environment has been performed and the results have been tabulated in a two-volume EPRI report.

A general methodology for the analysis of electrical grounding systems is presented. Earth is represented as a two layer semiinfinite region. An equivalent circuit model of the earth embedded electrodes and conductive soil is developed via numerical lution of Laplace equations. The equivalent circuit model, together with the electric power system network, represents a large scale network which is solved via the modified nodal analysis method. The procedure enables accurate analysis of complicated grounding systems and computation of touch, step and transfer voltages. Effects of tower footing resistance, counterpoised wires, types of system faults (phase to ground, line to line, etc.) can be analyzed. Practical grounding systems can be easily analyzed because model reduction techniques can be incorporated in the analysis method. The methodology is demonstrated with the study of a nontrivial grounding system analysis problem.

A technique is presented for solution of the inverse problem of calculating the electric field on a planar surface from the electric field specified on a nearby surface. An integral equation is derived that relates two orthogonal components of the electric field on the nearby surface to the respective components of the plane wave spectrum of the planar electric field. The integral equation is solved by an iterative technique, and the planar near field is calculated by an inverse Fourier transform of the plane wave spectrum.