RESONATOR

A resonator assembly and method are disclosed. The resonator assembly comprises: a resonant chamber defined by a first wall, a second wall opposing the first wall and side walls extending between the first wall and the second wall; a first resonator comprising a first resonator element and a first resonator cap, the first resonator element having a first grounded end and an first open end, the first resonator element being grounded at the first grounded end on the first wall and extending into the resonant chamber, the first resonator cap having a first grounded portion and an first open portion, the first resonator cap being grounded at the first grounded portion on the second wall and extending into the resonant chamber to at least partially surround the first open end of the first resonator element with the first open portion for electrical field loading of the first resonator element by the first resonator cap; and a second resonator comprising a second resonator element and a second resonator cap located for electrical field loading of the second resonator element by the second resonator cap, the second resonator element being located for magnetic field coupling between the first resonator element and the second resonator element. In this way, a compact resonator assembly is provided having high operational performance. The provision of resonators having resonator elements and resonator caps helps to reduce the height of the resonator assembly to around one eighth of the operating wavelength. The provision of the resonator caps helps to contain the electrical field from the resonator elements, which enables adjacent resonator elements to be located closer together to provide for enhanced magnetic field coupling therebetween.