A vortex radio emission beam is obtained
Scientists from the Swedish Institute of Space Physics and the University of Padua (Italy) obtained a vortex beam of radio emission in a simple laboratory experiment.
The formation of vortices is associated with the appearance at the wavefront (a surface at all points of which the light vibrations have the same phase) of singular points similar to screw dislocations – two-dimensional crystal lattice defects considered in solid state physics. The amplitude of oscillations at the singular point itself vanishes, and when walking around it, the phase changes by 2π. Dislocation dramatically changes the appearance of the wavefront, initiating a transition from traditional “sheets” to a single surface with a characteristic helical structure, according to Computerra.
The first experiments on the creation of optical vortex beams, the projection of which on a flat surface resembles a ring, were carried out quite a long time ago. Now laser “vortices” are used, for example, in optical tweezers for manipulating micrometer objects. Electronic analogs of such beams were demonstrated last year.
Scientists worked with the radio-frequency version of the vortex beam in a special anechoic chamber in the laboratory of Uppsala University. For the experiments, a 2.4 GHz frequency was chosen, which falls into the Wi-Fi range, and a conventional “wave channel” antenna. The beam acquired the necessary properties after reflection from an eight-stage reflector in the form of a spiral staircase installed next to the antenna, the axis of which coincided with the axis of the beam.
Two receiving antennas, located seven meters from the reflector, helped to evaluate the results. One of them was fixed, and the second was moved in a plane perpendicular to the axis of the radio beam; by making measurements, physicists obtained an intensity distribution with an expected dip in the center.
In the near future, these experiments will be carried out in real conditions – at greater distances and in the open air. According to one of the participants in the study, Fabrizio Tamburini, this technology can be used in wireless communication: it will provide additional possibilities for encoding information, and the cost of user devices prepared for working with vortex beams will increase slightly.