Research Of Leaky Wave Antenna Based On Spoof Surface Plasmon Polaritons

Leaky wave antenna(LWA)based on spoof surface plasmon polaritons(SSPPs)excited is a traveling wave antenna.It has been widely used in high-resolution radar and real-time spectrum analysis,due to its high directivity,high radiation efficiency,easy feeding,miniaturization of planar electromagnetism structure and easy integration,being a research focus in recent years.In this thesis,the characteristics of this kind of antenna are studied.The main contents of two parts:in the first part,a new type of SSPPs unit cell structure is designed based on the research of the current unit cell structures;in the second part,two different types of leaky wave antennas are designed based on the study of the unit structure.The main contents are listed as follow:Firstly,the basic characteristics of SSPPs unit structure are studied theoretically,and a new type of SSPPs unit structure is designed based on the principle of this kind of structure.The SSPPs unit cell can be categorized into two types:open structure(e.g.H/U-type grooves)and closed structure(e.g.slotted rectangles).Based on the simulation results,it is found that the asymptotic frequency of the open structure is lower than that of the closed type(which means that the closed type unit structure has a larger working frequency band),therefore a novel type of SSPPs unit structure with trapezoidal slotted structure,is proposed,and the dispersion characteristics of this kind of structure are studied,which provides a theoretical basis for the design of SSPPs leaky wave antennas.Secondly,a wide-band leaky wave antenna based on the new SSPPs unit structure is designed,which works at 7?15GHz(relative bandwidth of 72.73%).The antenna consists of two parts:one is a spoof surface plasmon polaritons transmission line,the other is a circular patch with asymmetric structure.It has stable high radiation gain and enables continuous beam scanning(from backward to forward direction).Its beam scanning angle is 69°.The simulation results are in good agreement with the engineering measured results,and the measured gain variation is only 1.64 d B.Compared with the same type of antennas previously reported,the strong point of this antenna lies in its smaller overall size,which is more conducive to the integration of modern wireless antenna systems.Thirdly,a circularly polarized leaky wave antenna based on the new SSPPs unit structure is designed.By introducing perturbation into the modulation patch with a quarter wavelength difference on both sides,the electric field direction on the antenna surface will be changed,so that it can generate circularly polarized waves.A PEC reflector is added at a distance of about 0.3?₀(?₀ being the vacuum wavelength for the broadside radiation)to improve the antenna gain,achieving a gain increases of about 3d B.The radiation gain of the antenna in working bandwidth is stable at about12.77d Bic,and the 3d B axial-ratio bandwidth is 40%.