Cavity-restrained multistacked dielectric omnidirectional antenna for microwave and millimetre-wave wireless communications

A novel microwave omnidirectional antenna is proposed for wireless communications. This antenna is constructed with cavity-restrained multistacked dielectric discs. Vertical polarised omnidirectional radiation patterns are obtained from radiative ring slots in the side wall of dielectric-metal cavities operating in the TM_01δ mode. High omnidirectional gain is realised with stacked cavities with multiradiative slots. Ring slots between the adjacent cavities are used to ensure the excitation of the desired radiating mode in phase, which actually eliminates the feed network. A special technique is adopted for excitation of the antenna from the coaxial line, with which very good matching is achieved