Circular Composite Dielectric Waveguides and their Applications in HEll Mode High Power Microwave Heating Systems

The wave propagation in circular shielded dielectric waveguides consisting of composite PTFE and BaTiO3 loaded PTFE material is studied both theoretically and experimentally. Using the developed theory the main parameters of the structure (cut-off and geometrical characteristics) were optimised for X-band BaTiO3/PTFE transmission systems. A minimum launching efficiency of 88% was achieved. Microwave absorption and subsequently conversion to heat was obtained with a specially developed solid load which could successfully operate up to 3 KW power levels. The low and high frequency breakdown of He/O2 gases, as required by divers working at depth, were studied in view of their importance in the operation of dielectric waveguide underwater transmission systems.