In this study, a novel technique to change the transmission frequency of a stealth radome using a mutual inductance effect is proposed. A stealth radome has a specific transmission frequency determined by an internally inserted frequency selective surface (FSS). The electromagnetic characteristics of the FSS inserted in the stealth radome is changed by adding an FSS film with a grid pattern. Therefore, this method can be applied to an existing stealth radome by inserting various new FSS films between the radome and the antenna. The stealth radome specimen is simplified for verification. The electromagnetic performance is measured with a free space measurement. As a result, it was confirmed that the additional FSS film causes mutual inductance and the transmission frequency can be changed. It was also confirmed that the electromagnetic performance changes depending on the symmetry and area of overlap of the additional FSS film and the original FSS inserted in the stealth radome. If the method overlapping the additional FSS film is not symmetrical, it is confirmed that the electromagnetic performance varies according to the TE and TM modes. Therefore, when applying this technique, an additional FSS film should be applied considering the position of the FSS inserted in the stealth radome.