Abstract: This paper compares the E-field distributions of two horizontally polarized radiation-wave simulator with different wire grating structure. The antenna wires of one simulator are uniformly distributed on the ground, while the other simulator’s antenna wires are converged to several groups at the end. Meanwhile, the influences of wire number and group number on the radiated field are discussed. Results show that the E-fields below the bicone apex are not affected by the wire grating structure. While in other positions, the E-field characteristics of the two simulators are different: when the wire number is the same, the simulator with uniform wire will increase the E-field amplitude by 5% to 20%, but its rise time increases about 10% at the same time; the simulator whose antenna wires are converged shows lower E-field amplitude, but its rise time is shorter. Besides, the latter is easy to establish in practice. On the other hand, increasing the wire number and wire group is helpful to improve the radiation amplitude, but the improvement reduces gradually. If the wire number increases from 24 to 96, the rise time can be improved by about 10%, but the half width of radiated E-field shows little difference. The increase of group number will lead to longer rise time. Taking into account the variation law of the E-field and the complexity to establish, the wire number of the simulator with uniform wire can be set to 48, and for the simulator whose antenna wires are converged, the group number can be set to 16.