Broadband coupling to comb-structure

Claim 1

IN COMBINATION: A SECTION OF HOLLOW WAVEGUIDE, MEANS DISPOSED WITHIN SAID WAVEGUIDE FOR FORMING A SLOW WAVE CIRCUIT COMPRISING A COPLANAR ARRAY OF RODS LONGITUDINALLY DISTRIBUTED THEREIN, EACH OF SAID RODS EXTENDING TRANSVERSE TO THE GUIDE AXIS IN A DIRECTION SUBSTANTIALLY PARALLEL TO ONE ANOTHER AND EACH ROD BEING EQUALLY SPACED FROM THE NEXT ADJACENT ROD, EACH ROD HAVING ONE END SHORT-CIRCUITED TO ONE WALL OF THE WAVEGUIDE AND THE OTHER END OPEN-CIRCUITED, MEANS FOR COUPLING ELECTROMAGNETIC WAVE ENERGY TO SAID SLOW-WAVE CIRCUIT COMPRISING A COAXIAL TRANSMISSION LINE HAVING AN OUTER AND AN INNER CONDUCTOR, THE OUTER CONDUCTOR BEING SHORT-CIRCUITED TO SAID ONE WALL OF SAID WAVEGUIDE, THE INNER CONDUCTOR FORMING A COUPLING ELEMENT EXTENDING THROUGH SAID ONE WALL AND ACROSS THE GUIDE TO THE OPPOSITE WALL OF SAID GUIDE AND BEING SHORT-CIRCUITED THERETO, SAID COUPLING ELEMENT BEING SUBSTANTIALLY PARALLEL TO AND COPLANAR WITH THE RODS OF SAID ARRAY WITH THE SPACING BETWEEN SAID COUPLING ELEMENT AND THE NEXT ADJACENT ROD BEING SUBSTANTIALLY THE SAME AS THE SPACING BETWEEN ADJACENT RODS OF SAID ARRAY, AND MATCHING MEANS POSITIONED ADJACENT TO SAID COUPLING ELEMENT FOR MATCHING THE COUPLING ELEMENT TO THE ARRAY.