Surface Charges Guided Quasi‐TEM‐mode Microwave Propagation along Dielectric Nanowire

According to Maxwell's equations, it is generally believed that a single‐conductor transmission line cannot allow TEM‐mode electromagnetic wave propagation. This is based upon the assumption that dielectric material is isolated from the environment. Here we have demonstrated both experimentally and theoretically that when the surface bound electrostatic charges of a dielectric nanowire (NW) is in function, a single‐conductor transmission line with dielectric NW as the signal line could guide quasi‐TEM electromagnetic waves. It is proposed that the surface electrostatic charges of ZnO NWs would respond rapidly to the external electric field in the direction normal to the surface through displacement polarization, thereby maintaining a zero electric field inside NW and inducing an effective variation in boundary shapes transversely. In the direction parallel to the surface, the outermost bound negative charges constitute a like‐charge thin‐layer system. Due to the in‐plane translational symmetry of this system, its interaction with electromagnetic waves satisfies quasi‐momentum conservation, allowing the Lorentz‐force‐induced momentum to be transferred longitudinally among the like‐charges. This process gives rise to a displacement current that sustains the magnetic field at the surface, enabling quasi‐TEM‐mode microwave guidance.