Abstract: Objectives In order to improve the application effect of button-type metal diverter strips for ship-radome lightning protection, their ionization characteristics need to be investigated in an environment in the vicinity of coming lightning leaders. Methods Here we report the experimental results of DC breakdown voltage of button-type diverter strips with various button spacings, button shapes, and diverter strip lengths, to compare their ionization capability. Accordingly, we carried out a calculation of the electrostatic field distribution for corresponding strips. Results Our experimental results show that, with the increase of diverter strip length, the breakdown voltage of diverter strip has a saturation effect, and that, with a fixed length of diverter strip, a larger spacing between metal buttons results in the higher breakdown voltage. Moreover, the breakdown voltage of elliptical-button diverter strip is the lowest, roughly 77% of circular-button ones. Furthermore, the breakdown voltage of rectangular-button diverter strips is about 86% of that for circular-button diverter strips. Our electrostatic field calculations suggest that the electric field intensity distribution of button-type diverter strip is relatively high at both ends and low in the middle, and that the smaller spacing between buttons, the greater electric field strength of the gap at both ends. Compared with the circular-and rectangular-button diverter strip, the electric field intensity at both ends of the elliptical-button diverter strip is the largest. The strength of electric field between the two ends of the diverter strip gap decreases nonlinearly with the increase of the length of diverter strip, thus explaining the phenomenon that the breakdown voltage varies in the experiment due to variation in the shape and specification of the buttons. Conclusions Results here provide a basis for the optimization of button-type metal shunt strips, thereby opening doors to enhancement of lightning protection effects for radomes.