Design of a broadband blade and DRA hybrid antenna with hemi-spherical coverage for wireless communications of UAV swarms

Blade antennas are widely used for airborne communications owing to their light weight and wide bandwidth. However, radiation pattern of a blade antenna is monopole-like and yields a deep null towards its top direction. This will cause serious blind spots for the aircraft towards its top and bottom directions, which is not desirable for future avionic networks. To solve this issue, a dielectric resonator antenna (DRA) is added to the blade antenna and forms a new design. A rectangular DRA is adopted in this paper to illustrate the main idea. The rectangular DRA operates in the lowest TE₁₁₁ mode and its radiation pattern covers the high elevation angle region. The blade antenna, on the other hand, has a nearly omni-directional radiation pattern in the low elevation angle region. Combination of the DRA and blade antenna can provide a hemispherical coverage with relatively small ripples. A closed-form model is presented to explain the radiation mechanism of the hybrid antenna. For verification, a prototype antenna is designed, fabricated and measured. Its impedance bandwidth covers 1.3–2.4 GHz and its radiation patterns yield small ripples in the top hemi-sphere until 2.1 GHz.