Research And Application Of Vortex-beam Antenna Based On SSPP

As an important support for the development of modern society,wireless communication technology bears the needs of hundreds of millions of users.Today,the available microwave spectrum is becoming increasingly crowded,a new generation of wireless mobile communication technology with higher speed,higher efficiency and more intelligence is urgently needed to further improve the system capacity and spectrum utilization.Scientists have found that in addition to frequency,phase and polarization,electromagnetic wave has a new dimension of orbital angular momentum,which can greatly increase the communication capacity without increasing the bandwidth of wireless system.Therefore,the vortex beam carrying orbital angular momentum has become a new direction to improve the communication rate and coding efficiency.It can be used in multistage modulation and improving spectrum utilization,which has a great prospect of development and application.The surface wave transmission of Spoof Surface Plasmon Polariton(SSPP)supported by subwavelength metal groove structure has been widely concerned.It has a similar dispersion characteristics to Surface Plasmon Polariton(SPP),and its dispersion characteristics can be adjusted by changing the geometric parameters of the matal groove structure.At the same time,its easy processing,easy integration,easy realization and other properties further expand its development and application prospects.In this thesis,a new type of vortex beam antenna with orbital angular momentum is studied in detail on the basis of SSPP circular loop leaky-wake antenna which have some unique characteristics and advantages.By combining with variable capacitance and other devices,the research of dynamic adjustable vortex beam antenna is carried out.The main work contents are as follows:1.Firstly,the classification and radiation principle of the leaky-wave antenna are introduced,and then an SSPP leaky-wave antenna with 8 GHz center frequency is designed by impedance surface modulation method.The leaky-wave antenna can be scanned from backward to forward by changing the frequency continuously.2.The theoretical model of circular loop leaky-wave antenna is established,the near and far field components of radiated electromagnetic wave are calculated by the integral method.It is verified that the vortex phase factor exists in the component of the electromagnetic field,which verifies the feasibility of vortex beam generation by circular loop leaky-wave antenna.3.On the basis of the previous analysis,we connected the linear leaky-wave antennas end to end to form the circular loop leaky-wave antenna,and designed an circular leaky-wave vortex beam antenna based on SSPP.The antenna operates in the range of 6.5GHz-9.5GHz which having different orbital angular momentum modes.The antenna can simultaneously transmit left-hand circularly polarized and right-handed circularly polarized vortex beams,which is easy to be reused further.4.In order to further improve the multiplexing ability of the antenna structure,a variable capacitance element is introduced into the antenna.At present,the angular momentum mode can be adjusted to four modes at the fixed frequency,further increasing the practicability of the structure.