| Spoof Surface Plasmon Polaritons(SSPP)has been in the spotlight of research in recent years due to its strong directivity,high radiation efficiency,and miniaturization.This thesis mainly focuses on the research of SSPP-based dual-beam leaky-wave antenna and the major results are as follows:1.A transmission line based on composite spoof surface plasmon polaritons(SSPP)waveguides is proposed.The transmission line can generate three independent transmission channels by exciting two modes inherent to the hole and groove structures.The dispersion characteristics of the composite transmission line are simulated and analyzed.2.Based on the composite SSPP waveguide,A dual-beam scanning leaky wave antenna is proposed.In light of the sinusoidal modulation theory,two sinusoidal modulations with different periods are introduced to the composite SSPP waveguide structure to excite two beams.Dual-beam scanning through the broadside is achieved using only the-1st space harmonics of the two modes,hence avoiding the instability of the-2rd space harmonic.Within the operating frequency range of 0.62～0.85 THz,the gain ranges from 13.5d Bi to 17 d Bi for the backward beam,and from 6d Bi to11.8d Bi for the forward beam.The antenna can accomplish continuous backward through broadside to forward beam scanning with a total scanning range of 116° and an average efficiency of about 92%.By comparing with the relevant literature in recent years,it shows that the antenna proposed in this thesis has better spatial scanning characteristics and high gain and efficiency.3.A dual-beam leaky-wave antenna based on mutually coupled double-layer SSPP transmission lines is proposed.There are two antisymmetric transmission lines based on U-groove waveguides on the upper and lower layers of the antenna,respectively.By comparing the dispersion curve of the single-layer U-groove waveguide and that of the double-layer anti-symmetric U-groove waveguide,it is found that the double-layer structure exhibits a stronger field confinement.Based on the mutually coupled double-layer transmission line,circular radiating patches with different parameters are loaded on the upper and lower layers of the antenna,respectively.Hence the electromagnetic waves in the transmission line can be effectively radiated into the free space in the form of two beams.The results show that the antenna has excellent spatial scanning capability in the microwave frequency range of 11 GHz to 14 GHz,the scanning angle of the backward beam is from-90° to+9°,and that of the forward beam is from-8° to +59°.A total scanning angle of149°is achieved in the given frequency band.4.By combine that double-layer transmission line structure with the sinusoidal modulation theory,A novel SSPP leaky wave antenna with periodic modulation based on double-layer transmission lines is proposed.Different periods of sinusoidal modulation are introduced into the upper and lower double-layer waveguide structures,respectively,to generate a dual-beam radiation.Through simulation analysis,the antenna achieves a 52° scanning range and its maximum radiation gain is 12 d Bi. |
PDF Full Text Request