Planar Waveguide Hybrids for Very High Power RF

摘要

Two basic designs have been developed for waveguide hybrids, or 3-dB couplers,211u001ecapable of handling hundreds of megawatts at X-band. Coupling is provided by one 211u001eor two connecting waveguides with h-plane junctions and matching elements. In the 211u001eformer case, the connecting waveguide supports two modes. Small apertures and 211u001efield-enhancing e-bends are avoided to reduce risk of rf breakdown. The h-plane 211u001esymmetry also allows the use of over-moded rectangular waveguide in which the 211u001eheight has been increased to reduce field amplitudes without affecting the 211u001escattering matrix. The theory and designs are presented, along with the results 211u001eof prototype tests of functionality and power-handling capability. Such a device 211u001eis integral to the rf pulse compression or power distribution systems (2) of the 211u001eNext Linear Collider (NLC) (1) for combining, splitting, and directing power. 211u001eThis work was motivated by the observation of rf breakdown at power levels above 211u001e200 NW in conventional and modified magic-T's.