<Li> Electromagnetic energy is not converted from the surface wave field to another form of energy (except in leaky or lossy surface waves) such that the wave does not transmit power normal to the interface, i.e. it is evanescent along that dimension . </Li> <Li> In optical fiber transmission, evanescent waves are surface waves . </Li> <Li> In coaxial cable in addition to the TEM mode there also exists a transverse - magnetic (TM) mode which propagates as a surface wave in the region around the central conductor . For coax of common impedance this mode is effectively suppressed but in high impedance coax and on a single central conductor without any outer shield, low attenuation and very broadband propagation is supported . Transmission line operation in this mode is called E-Line . </Li> <P> The surface plasmon polariton (SPP) is an electromagnetic surface wave that travels along an interface between two media with different dielectric constants . It exists under the condition that the permittivity of one of the materials forming the interface is negative, while the other one is positive, as is the case for the interface between air and a lossy conducting medium below the plasma frequency . The wave propagates parallel to the interface and decays exponentially vertical to it, a property called evanescence . Since the wave is on the boundary of a lossy conductor and a second medium, these oscillations can be sensitive to changes to the boundary, such as the adsorption of molecules by the conducting surface . </P>

Describe the difference between a body wave and a surface wave