Trihedral corner reflectors (or TCR) are widely used as passive calibration targets for SAR imagery. This work focused on the quantification of several causes of error to be taken into account during the design and construction phases of a target of this type. The characterization was made using FEKO electromagnetics software, to simulate multiple configurations and to later quantify the losses due to the different sources of error. With the results it was possible to establish design tolerances for a TCR of fixed inner length, which will be useful in the subsequent construction process, and they showed potential for more comprehensive studies using a similar methodology.