The present invention relates to a transition arrangement comprising a first surface-mountable waveguide part and a second surface-mountable waveguide part, each of the first and second surface-mountable waveguide parts comprising a first wall, a second wall and a third wall, which second and third walls are arranged to contact a dielectric carrier material, all the walls together essentially forming a U-shape, where the first and second surface-mountable waveguide parts are arranged to be mounted on the dielectric carrier material in such a way that the first and second surface-mountable waveguide parts comprise ends which are positioned to face each other. The transition arrangement further comprises an electrically conducting sealing frame that is arranged to be mounted over and covering the ends, where the electrically conducting frame has a first wall, a second wall and a third wall, where the second and third walls are arranged to contact the dielectric carrier material, all the walls together essentially forming a U-shape.