Experimental procedures are developed for the determination of input impedance, gain and scattering cross-section of an antenna as a function of its load, from a minimum of three scattering amplitude measurements. The procedures involve terminating the antenna with a calibrated reactive load, whose variation causes a maximising and minimising of the antenna scattering cross-section; the loads associated with certain cross-sections are plotted on a Smith chart, and through geometrical constructions are related to input impedance; formulas are developed relating maximum and minimum cross-sections to antenna gain and cross-section. Experimental verification of the procedures is presented and their advantages and disadvantages are discussed.