A method of determining an amplifier performance is provided. One embodiment establishes a number of amplifier performance constraints. A search is then conducted for an input and an output disk that satisfy the amplifier performance constraints. A vector index is then generated that includes a load reflectance S.sub.L and a generator reflectance S.sub.G at a number of different radio frequencies. The amplifier performance constraints are then input into the vector index and the load reflectances S.sub.L and generator reflectances S.sub.G that meet the amplifier performance constraints are determined.