This study involved the characterization of the individual elements in a prototype hyperthermia applicator based on the sector-vortex phased array. The results showed substantial variations in the amplitudes and phases of the pressure outputs of elements driven with the same input signal. However, these variations produced only a slight asymmetry in the side lobes and did not affect the 3-dB beamwidth of the characteristic focus. Compensating for the phase variations increased the focal intensity and improved the symmetry of the overall field pattern. Similar improvement was found when compensation was used for the synthesis of an annular field pattern. The fact that this compensation could be completely implemented in software demonstrates the flexibility of phased arrays.