I have seen feeds with insulators resembling spacers - which are not continuous - to keep distributed C down. Ive seen foam dielectrics etc I was thinking of a new wire design which could be useful in soma applications eg where the volts isn't too high and corrosion risk low.. I was thinking that if a process could deposit insulation in sections the distributed C would reduce a fair bit and enable pretty broad band lower loss Ls.. something like the sketch.. S