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The Mapper of the IGM Spin Temperature (MIST) is a new ground-based,single-antenna, radio experiment attempting to detect the global 21 cm signalfrom the Dark Ages and Cosmic Dawn. A significant challenge in this measurementis the frequency-dependence, or chromaticity, of the antenna beam directivity.MIST observes with the antenna above the soil and without a metal ground plane,and the beam directivity is sensitive to the electrical characteristics of thesoil. In this paper, we use simulated observations with MIST to study how thedetection of the global 21 cm signal from Cosmic Dawn is affected by the soiland the MIST beam directivity. We simulate observations using electromagneticmodels of the directivity computed for single- and two-layer models of thesoil. We test the recovery of the Cosmic Dawn signal with and without beamchromaticity correction applied to the simulated data. We find that oursingle-layer soil models enable a straightforward recovery of the signal evenwithout chromaticity correction. Two-layer models increase the beamchromaticity and make the recovery more challenging. However, for the model inwhich the bottom soil layer has a lower electrical conductivity than the toplayer, the signal can be recovered even without chromaticity correction. Forthe other two-layer models, chromaticity correction is necessary for therecovery of the signal and the accuracy requirements for the soil parametersvary between models. These results will be used as a guideline to selectobservation sites that are favorable for the detection of the Cosmic Dawnsignal.

Simulating the detection of the global 21 cm signal with MIST for different models of the soil and beam directivity