An assembly of waveguides and coupling apertures located within walls separating the waveguides is formed within a planar configuration. The coupling apertures are arranged either singly or in pairs, with one coupling aperture behind the other coupling aperture, to provide for a division of power between...http://www.google.fr/patents/US4812788?utm_source=gb-gplus-shareBrevet US4812788 - Waveguide matrix including in-plane crossover
