  Spheres, cylinders, cones, cuboids have been used in the literature to
generate photonic jets at the back of these structures when illuminated by
plane waves. We are working on the generalization (which we call
electromagnetic jet) of this concept in guided structures in the microwave
domain. The electromagnetic jet can be obtained from a rectangular waveguide
loaded with dielectric. In order to use the electromagnetic jet as a localized
measurement tool, it is therefore necessary to address the adaptation between
an empty rectangular waveguide and a loaded guide. This is the object of the
work presented here, where two solutions are compared.
