Ring-shaped open-ended resonant cavities

Ring-shaped open-ended resonant cavity (RSOERC) is a development of a construction of the open-ended resonant cavity (OERC). It may be introduced as a body of rotation, which is formed by turning of a cross section of biconical open-ended cavity resonator around axis, which does not pass through this cross section. We see that this RSOERC can be presented as a combination of four cut cones. The two bigger ones are external, the two smaller ones are internal. Resonant volume of this construction is formed by inside surfaces of the first pair of two critical sections of resonant cavity and and external surface of the second pair of cones. The peculiarity of the discussed construction is a possibility of passing some tube-shaped object through critical sections and inner volume of the resonator (for biconical OERC such an object must be bar-shaped). Ring-shaped resonant cavities, as well as traditional open-ended resonant cavities, can have many interesting and important applications. We discuss these applications in detail.