A uniform asymptotic high-frequency solution Is developed for the diffraction of (E-polarised) electromagnetic plane waves by a two-part impedance strip. Uniform expressions for the interactions up to third order between the edges of the strip, including the conversion of surface-wave fields into space-wave fields, and vice-versa, via edge or junction diffraction, are obtained. The solution is based on a spectral iteration technique consisting of taking the spectral representation of the n-tuply diffracted field by one edge as the incident field for a half-plane (or a two-part plane) associated with the other edge (or junction) where the (n + 1)th diffraction will take place. The analysis is then performed through the Wiener-Hopf technique for the (n + 1)th diffraction. Bistatic diffraction patterns are obtained for different values of the surface impedances of the strip.