Surface-standing-wave formation via resonance interaction of a finite-length conductive rod with microwaves

Abstract

The resonant response of a thin conducting rod with a finite length irradiated by microwaves polarized along its axis is observed. By using a thermoelastic optical indicator microscope it is shown that rod with a length of several half- wavelengths can serve as a resonator for axial surface waves. It is facilitated by noticeable reflections (approximately 30%) from the rod edges conditioned by the unique distributions of Sommerfeld wave fields along a rod. The presence of a weak axial electric field component of surface waves ensures an easy coupling with the incident plane wave polarized along the rod axis and excites the resonator. Visualization of distributions of the near-field magnetic component of surface standing waves in the vicinity of a rod allows the exploration of three longitudinal modes of a resonator with low orders. The possibility of controlling the resonant frequency by changing the length and diameter of the rod, as well as the electromagnetic characteristics of the environment, are studied. The phenomenon under study can be used to create wavefront shaping metasurfaces and for studies of the properties of a dielectric medium in the microwave region. As Sommerfeld waves propagate on the surface of a cylindrical resonator, the resonant properties are sensitive to the dielectric permittivity of the surrounding medium, which will open up the potential for using the suggested resonator in sensing applications, which is experimentally demonstrated.