sheat wave

Sheath waves are high-frequency electromagnetic waves that propagate on the cable sheath, correctly speaking, on the shielding ofcoaxial cables. The circuit of the sheath waves closes via the ground line.

Sheath waves can be caused by induction, by different ground potential or by faulty line matching when converting asymmetrical signals into symmetrical ones, as for example in broadcasting technology when connecting symmetrical antennas to the asymmetrical coaxial antennacable. If the impedance matching or the cable matching by the balun or the balancing element is not correct, then sheath waves can occur which propagate on the shielding of the coaxial cable.

Sheath waves can be reduced by sheath current filters or by upstream common- mode filters which suppress common-mode interference and provide decoupling of the electromagnetic interference fields.