Development of Air-Core Beamforming Antenna With 24 GHz Band 25 W Class Power Feed Circuit

In this study, we have developed a radial line-slot antenna that forms an air-core beam suitable for wireless power transmission. By using the Laguerre-Gaussian mode (OAM-mode), air-core beam can be formed in which the center intensity is null. This feature is useful to avoid interference with equipment placed in the center of the receiving antenna. The desired aperture plane distribution was obtained from the analytical solution of the beam, and the slot antenna pair that realizes the aperture plane distribution was designed. Four coaxial probes with excitation phases differing by 90 degrees each were used to excite m=3 rotational modes in the radial waveguide. The diameter of the designed 24-GHz RLSA was 300 mm, and the total output power of the developed 4-port feeding circuit was 25 W. Using these devices, we plan to conduct proof of concept for wireless power transmission to drone.