| Spoof surface plasmon polaritons(SSPPs)are electromagnetic waves which have similar dispersion characteristics to surface plasmon polaritons(SPPs)and propagate along the surface of periodic metal structure.The prominent advantages of SSPPs structure are that its dispersion characteristics and the ability to confine electromagnetic waves are completely determined by its structural size.After the presentation of SSPPs,it has been widely investigated and applied in terahertz and microwave frequencies.This thesis mainly studies the transmission lines and leaky-wave antennas based on SSPPs.The main contents of this thesis are as follows:Firstly,the circuit model method and resonance method of analyzing the dispersion characteristics of SSPPs structure are introduced,and the results of different methods are compared and expounded.Then,the method of obtaining the loss characteristics of SSPPs transmission lines is given,and its effectiveness is verified.Secondly,a novel three-dimensional(3D)integrated SSPPs transmission line is proposed,which supports the propagation of electromagnetic waves by periodically arranging 3D rivet-like unit cells on a metal strip.The dispersion characteristics,highorder modes and propagation characteristics of the proposed transmission line are studied.The dispersion characteristics of the unit cell can be tailored by multiple variables,making it suitable for a variety of scenarios.And then,the ohmic and dielectric losses of the proposed transmission line are simulated and compared with the typical SSPPs transmission lines,microstrip line and coplanar waveguide respectively.The ohmic and dielectric losses of the proposed transmission line are comparable to single side comblike transmission line and hole arrays transmission line respectively.The proposed transmission line is fabricated and measured.The measured results are close to the simulations,indicating that the proposed transmission line can support the propagation of SSPPs.In addition,the variation in the width of metal strip can form fully-open structures or semi-open structures to accommodate different types of integrated circuits.Thirdly,a novel integrated mode composite transmission line(IMCTL)is proposed,which consists of inner and outer transmission lines.The dispersion characteristics,electromagnetic field distributions and propagation characteristics of the inner and outer surface IMCTL are studied.Different dispersion characteristics of the inner and outer surface IMCTL can be obtained by adjusting the geometric parameters of the unit cell,making it suitable for engineering applications.The circuit models of the inner and outer surface IMCTL are discussed and analyzed,and the effectiveness of circuit models for obtaining dispersion and propagation characteristics is verified by comparison.Then,the ohmic and dielectric losses of the inner and outer surface IMCTL are simulated and compared with typical transmission lines.The ohmic and dielectric losses of the inner IMCTL are significantly higher than microstrip line and SIW respectively,and the ohmic and dielectric losses of the outer surface IMCTL are comparable to double sides comblike transmission line and rivet-like transmission line respectively.The proposed inner and outer surface IMCTL are fabricated and measured.The measured results of transmission lines are basically in agreement with the simulations,the measured insertion losses of inner IMCTL are within 1.77±0.64 dB from 5.5 to 10.0GHz.And the measured insertion losses of outer surface IMCTL are within 3.21±1.22 dB from 2.0 to 6.0GHz.The IMCTL supports high-frequency transmission in the inner transmission line and lowfrequency transmission in the outer surface transmission line with different propagation modes.It not only has the simple structure and high-pass characteristics of SIW,but also has the adjustable dispersion and low-pass characteristics of SSPPs transmission line.The IMCTL provides a new possibility for the development of integrated high-performance multiband microwave and wireless communication systems.Fourthly,the odd-mode and even-mode SSPPs supported by complementary comblike unit cell and microstrip-type complementary comb-like unit cell are investigated.The dispersion characteristics and electric field distributions of the odd-mode and even-mode SSPPs are studied.Different high-efficiency conversion structures are proposed to realize the excitation of odd-mode and even-mode SSPPs transmissions.The odd-mode and even-mode SSPPs transmission lines are fabricated and measured.The measured data are basically in agreement with the simulated results,indicating that the transmission lines have relatively good transmission performance for odd-mode and even-mode SSPPs.The measured insertion losses of odd-mode complementary comb-like and microstrip-type complementary comb-like transmission line are within 2.58±1.67 dB and 2.58±1.23 dB from 3.0 to 10.0GHz,respectively.The measured insertion losses of the first and second even-mode complementary comb-like transmission line are within 3.65±1.33 dB and 3.60±1.25 dB from 5.0 to 16.0GHz,respectively.The measured insertion losses of evenmode microstrip-type complementary comb-like transmission line are within 1.66±1.18 dB from 2.0 to 12.0GHz.Then,the defected ground structures(DGS)are loaded into the microstrip-type complementary comb-like transmission line.The effects of the same DGS on odd-mode and even-mode transmission lines are analyzed,and the odd-mode and even-mode transmission lines with notch characteristics are proposed.The odd-mode and even-mode microstrip-type complementary comb-like transmission lines with notch characteristics are fabricated and measured.The measured results of the transmission lines are basically in agreement with the simulations.The notch frequency of odd-mode transmission line is 5.3GHz,and the notch frequencies of even-mode transmission line are 5.6GHz and 9.2GHz.The notch frequencies of transmission lines are determined by the geometric parameters of DGS,which has the advantages of compact size and high integration.Finally,the SSPPs single-beam and double-beam leaky-wave antennas based on the hole arrays and sinusoidally-modulated reactance surface are proposed,which are realized by sinusoidal modulation of the unit cell of hole arrays.The dispersion characteristics and propagation characteristics of the hole arrays are analyzed.Then,the single-beam leaky-wave antenna is studied,and the dual-beam leaky-wave antenna is designed by combining two single-beam leaky-wave antenna with different radiation angles.The proposed single-beam and double-beam leaky-wave antennas are fabricated and measured.The measured results of the single-beam and dual-beam leaky-wave antennas are close to the simulations.The measured radiation angles of single-beam leaky-wave antenna are 15.71o,20.0oand 25.71o at 9.5 GHz,10.0 GHz and 10.5 GHz,respectively.The measured radiation angles of the first beam of the dual-beam leaky wave antenna are 14.29o,18.57oand 24.29o at 9.5 GHz,10.0 GHz and 10.5 GHz,respectively.And the measured radiation angles of the second beam are 22.86o,28.57oand 32.86o at 9.5 GHz,10.0 GHz and 10.5 GHz,respectively.The proposed leaky-wave antennas have good directivity and frequency scanning characteristics,which can be applied to navigation systems and communication systems in closed buildings,and lay the foundation for developing high-performance SSPPs systems in the future. |
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