In this chapter, the fundamental antenna parameters are covered. The fundamental antenna parameters have already been covered in various handbooks. The unique perspective of this chapter is to map the theoreticalTheoretical principles to the practical simulationSimulation settings. This chapter includes a wide range of examples to illustrate the concepts behind the full-wave solver. Initially, the S-parametersS-parameters are introduced with standard examples. The steps for plotting are also illustrated with detailed explanation. The principal orthogonalOrthogonal cut planes are explained in detail with selective examples. The framework necessary to develop radiation patterns is introduced in this chapter. The technical details behind the settings for plotting far-fieldFar-field patterns are comprehensively covered. A detailed account on the co-polarizationCo-polarization and cross-polarizationCross-polarization patterns is covered in this chapter with several illustrations to add insights to the plots. The reasoning behind gainGain, port impedancePort impedance and mutual couplingMutual coupling is also covered.