Narrow EM-Wave Beam
Development of the Method for Producing Electromagnetic Wave Beams with Small Divergence
Tech Area / Field
- PHY-RAW/Radiofrequency Waves/Physics
8 Project completed
Senior Project Manager
Ryabeva E V
MRTI (Radio Techniques), Russia, Moscow
- Moscow Power Engineering Institute, Russia, Moscow\nRussian Academy of Sciences / Institute of Radioengineering and Electronics, Russia, Moscow
- US Department of Defense / Ballistic Missile Defense Organization, USA, DC, Washington
Project summaryThe main disadvantage of microwave wireless power transmission (WPT) is that the significant part of energy does not reach the given area of space due to diffractional pergence. As the transmission distance increase compared to diffractional length of the radiating antenna this disadvantage is most conspicuous. The size of the radiating and the receiving antennae must be selected so as not to exceed the diffraction length of the radiating aperture. It shouldn't go out the Fresnel zone for this.
The realization of the project will give an answer to the question of the possibility to obtain the small pergence beam. The aim is not to overcome repeatedly the diffractional boundary but to check upon some uncertain ideas, the realization of which does not contradict, to the existence of this boundary.
A new hypothesis was for the first time reported at the Second Wireless Power Transmission (WPT) Conference on 1995 in Kobe (WPT '95, report 4-2). This hypothesis is based on the presumption that if the continuous aperture is pided by separate, parts and these parts (subapertures) are situated on the radiating plate in the determinate order (uncompletely filled array) then the effectiveness of the WPT will be increased.
This hypothesis admits that generally speaking the size of the focal spot is decreasing by the increasing of the whole transmitting antenna size. The intercepted portion of energy in the receiving antenna is increased when its form is fixed. But the uncompletely filled antenna leads to the rise of a level of the dispersed energy (side lobes). It is felt by intuition that there must be some optimum. This problem is resolved by us correctly by the concrete example. The solution is based on finding the maximum of the ratio of the energy flow passing through the receiving antenna to a flow passing through the whole radiating antenna.
It happened that only WPT use the Fresnel zone in the microwave range. The theory -for Fresnel zone is widely elaborated for laser or optic, problems. But there the problem of increase of the diffraction length didn't occur so distinctly as in the Wireless Power Transmission because phase correctors and uncopletely filled apertures were practically not been used in optic. Hence the WPT is one of the rare branches where proposal works can be useful.
There are some other materials for development of the Method for improving wave beams and there are some new ideas.