Research On The Orbital Angular Momentum Antenna

In recent years, with the rapid development of wireless communication technology for information exchange, mobile terminal penetration gradually rise, the mobile Internet presents the development trend of the explosive To meet the demand of the growth of the mobile data service, urgently need to be more efficient and intelligent new generation of high-speed wireless mobile communication technology, to further improve the system capacity and spectrum efficiency. Orbital angular momentum(OAM) as a reuse technology in wireless communication gradually becomes a research hot topic.The openness and limitation of the electromagnetic spectrum prompt the development of the reuse technology. Now the reuse technology include: frequency division multiplexing(FDM) technique, which is the first generation(1G). 2G system introduces the time-division multiplexing(TDM, GSM, PDC,IS-136 etc.) and 3G network introduces the air separation reuse based on smart antenna(SDM). 4G networks joins the orthogonal frequency division multiplexing(OFDM), multiple input multiple output(MIMO) and cognitive radio(CR) The orbital angular momentum technology is considered to be one of possible transmission technology in the next generation mobile communication(5G) system.Given the importance of the orbital angular momentum, this paper corresponds to the application of the orbital angular momentum. The orbital angular momentum will be introduced from optical and quantum mechanics into electromagnetism By introducing Laguerre-Gaussian beams of orbital angular momentum, this paper expounds the basic theory and properties of orbital angular momentum, and orbital angular momentum expression was derived whether meet the solution of wave equation in free space, it determines the orbital angular momentum when the electromagnetic wave propagation in free space to satisfy the conditions It is the orthogonality of the orbital angular momentum in different order ensure it can serve as a kind of mode of transmission to be used into the field of wireless communication systemThis paper discusses the relation and distinction between spin angular momentum and orbital angular momentum. It describes the orbital angular momentum of the generation, transmission and detection. And important orbital angular momentum antennas are introduced, including circular array antenna, fixed reflector antenna, circular Vivaldi antenna and circular microstrip antenna. Introduced the method to producing the orbital angular momentum of electromagnetic beam, simulations of antenna systems with a series of different order number of the orbital angular momentum have been completed..A novel reflector antenna system generating electromagnetic field with orbital angular momentum is proposed. Composed of a monofilar conical-helix antenna and a 40-cm-diameter parabolic-reflector, the proposed antenna system can radiate electromagnetic field with OAM of order 2. Through the phase gradient method to test the radiation field phase diagram, it is judged as a second-order orbital angular momentum of the electromagnetic wave. And the influence of structure parameters of the feed on the orbital angular momentum has been analyzed.And then discusses the different forms of helix antenna feed producing the orbital angular momentum of different order. At the same time, the simulation of the offset reflector antenna produces orbital angular momentum electromagnetic beam is introduced.