In this paper, an in-band and out-of-band microwave wireless power-transmission characteristic analysis of a slot ring radome based on an approximate analytical method is proposed. The main contribution of this paper is that, in the approximate analysis of the ring radome, a unified expression of the incident field on the radome surface is derived with E-plane and H-plane scanning, and the ring is approximated as 30 segments of straight strips. Solving the corresponding 60 × 60 linear equations yields the electric current distribution along the ring strip. The magnetic current along the complementary slot ring is obtained by duality. Thanks to the fully analytical format of the current distribution, the microwave wireless power-transmission characteristics are efficiently calculated using Munk’s scheme. An example of a slot ring biplanar symmetric hybrid radome is used to verify the accuracy and efficiency of the proposed scheme. The central processing unit (CPU) time is about 690 s using Ansys HFSS software versus 2.82 s for the proposed method.

• In this paper, an in band and out of band microwave wireless power transmission characteristic analysis of slot ring radome based on an approximate analytical method is proposed.

• The main contribution of this paper is that for the approximate analysis of ring radome, the unified expression of the incident field on the radome surface with E-plane and H-plane scanning is derived, and the ring is approximated as 30 segments of straight strips. Solving the corresponding 60 × 60 linear equations yields the electric current distribution along the ring strip.

• The magnetic current along the complementary slot ring is obtained by dual. Benefitting from the fully analytical format of the current distribution, the microwave wireless power transmission characteristics are efficiently calculated using Munk’s scheme.

• An example of a slot ring biplanar symmetric hybrid radome verifies the accuracy and efficiency of the proposed scheme. The CPU time is about 690 s and 2.82 s for HFSS and the proposed method, respectively.