Five different single field emitters and emitter arrays with flat or nonflat collector structures were selected from the literature to simulate the actual emitting area of the tip. The Poisson’s equation was solved under two different assumptions of emitting behavior; uniform electron emission from the whole tip area, and electron emission from only small part of the tip area. It was observed that the geometry factor beta of an array is larger than that of a single emitter, which is believed to be partly responsible for exceedingly small computed value of emitting area alpha for multiemitter structures. Finite element analysis of single and multiemitter structures indicates that the large beta values are due to the interemitter interactions in an array.