  The response of the antenna is a source of uncertainty in measurements with
the Experiment to Detect the Global EoR Signature (EDGES). We aim to validate
the beam model of the low-band (50-100 MHz) dipole antenna with comparisons
between models and against data. We find that simulations of a simplified model
of the antenna over an infinite perfectly conducting ground plane are, with one
exception, robust to changes of numerical electromagnetic solver code or
algorithm. For simulations of the antenna with the actual finite ground plane
and realistic soil properties, we find that two out of three numerical solvers
agree well. Applying our analysis pipeline to a simulated driftscan observation
from an early EDGES low-band instrument that had a 10 m $\times$ 10 m ground
plane, we find residual levels after fitting and removing a five-term
foreground model to data binned in Local Sidereal Time (LST) average about 250
mK with $\pm$40 mK variation between numerical solvers. A similar analysis of
the primary 30 m $\times$ 30 m sawtooth ground plane reduced the LST-averaged
residuals to about 90 mK with $\pm$10 mK between the two viable solvers. More
broadly we show that larger ground planes generally perform better than smaller
ground planes. Simulated data have a power which is within 4$\%$ of real
observations, a limitation of net accuracy of the sky and beam models. We
observe that residual spectral structures after foreground model fits match
qualitatively between simulated data and observations, suggesting that the
frequency dependence of the beam is reasonably represented by the models. We
find that soil conductivity of 0.02 Sm$^{-1}$ and relative permittivity of 3.5
yield good agreement between simulated spectra and observations. This is
consistent with the soil properties reported by Sutinjo et al. (2015) for the
Murchison Radio-astronomy Observatory, where EDGES is located.
