Strumming resistant cable

A cable, comprising:

• a single central flexible elongated core having an electromagnetic signal carrier positioned therein for carrying electromagnetic signals;
• and
• a flexible elongated regular polygonal cross-section jacket having a plurality of vertices and surrounding the single central flexible elongated core, said jacket being comprised of a material which is impermeable to H.sub.2 O, the vertices comprising a helically wound phase shifter having a single-pitch direction extending longitudinally along substantially the entire length of said flexible elongated jacket for shifting a phase of an alternating force produced by a flow of fluid past the flexible elongated jacket, and having a plurality of phase shifting sections longitudinally distributed along the flexible elongated jacket, each of the phase shifting sections having a length less than one quarter the coherence length of the flexible jacket and shifting the period of the alternating force from zero to a period.