The characterization of electromagnetic devices commonly demand isolated environments with specific features, e.g. anechoic chambers. Nevertheless, the implementation cost of such structures is usually high and hence its availability is not always possible in the context of a research laboratory. This work proposes a methodology to find optimally configurated test setups for antennae characterization in open environments. Experimental and computational results indicate that the proposed methodology has the potential to provide the engineer a better understanding and control of the uncertainties levels associated with an antenna gain estimation setup.