Abstract The number of linear independent steering vectors effected by an ElectroMagnetic (EM) Vector Sensor (VS) and an EMVS array in cumulant domain is investigated in this paper. The upper bound and the lower bound for the number of linear independent steering vectors are both derived. The conclusions are useful for determining the number of non-Gaussian narrow-band signals whose DOAs can be uniquely identified by one EMVS or an array comprising multiple EMVSs. Simulation results validate the present derivations.