Gallery modes
Dielectric resonators - Microwave circuits

The higher the frequency, the smaller the resonator dimensions become. For example, at 30 GHz, the diameter of a resonator with a relative permittivity of 9, such as sapphire, is approximately 3 mm. In this case, with cylindrical resonators, modes of higher order than the fundamental TE mode _01δ are used; these are called gallery modes because the energy is confined to the periphery of the resonator  . They are listed