Multi-Mode Hybrid Antennas Using Liquid Dielectric Resonator and Magneto-Electric Dipole

This paper presents a new type of hybrid antenna that combines the multi-resonant modes produced by a liquid dielectric resonator antenna (DRA) and a magnetoelectric (ME) dipole. Such a combination could not be easily realized by using conventional solid dielectrics due to fabrication and air-gap problems. An aperture-fed ME dipole for 4.1 – 5.3 GHz is firstly designed using a standard structure and a relatively small dimension. Then, a hybrid antenna is built by loading the MEdipole with an aperture-fed cylindrical liquid DRA. Without increasing the antenna size and/or modifying the ME-dipole structure significantly, the hybrid antenna has realized a much wider bandwidth from 2.45 to 5.3 GHz after loading the liquid material. Moreover, it is found that the resonances of the MEdipole are not simply shifted to lower frequencies after using the dielectric loading, it has strategically combined the multiple resonances of the electric dipole, magnetic dipole, DRA and feeding slot. The mode combination principle and design guideline have been presented. As an example, a prototype of the proposed hybrid antenna has achieved a 73.5% fractional bandwidth with an electrical size of 0.66 × 0.66 × 0.16 λ03 at the centre frequency (3.88 GHz), over 5 dBi (up to 7 dBi) broadside gain, total efficiency > 80% and beam-width around 80 – 120° across the frequency band. The proposed hybrid antenna has advantages in terms of wide bandwidth, smaller size and simple structure compared with other ME-dipoles and traditional wideband antennas. The idea of this antenna design could be extended to other ME-dipole and DRA structures.