Abstract: As part of a microwave frequency device, such as a traveling wave tube, a novel slow wave structure is presented which comprises an electrically conductive wire formed into a series of interconnected loops which are spaced apart and parallel along a common axis, with said loops being arranged in alternate and intermediate pairs, the ones of said loops in said alternate pairs extending clockwise about said common axis and with the ones of said loops in said intermediate pairs extending counterclockwise about said axis and interconnecting portions of said wires joining ends of adjacent loops together to define a series electrical path which progresses from one end of the wire to the other seriatim through all said loops.