| Dielectric resonator antenna has been widely concerned and studied by domestic and foreign experts and scholars in recent years due to its small size,wide band width,low loss at high frequency,high radiation efficiency,easy excitation and other performance advantages and application value.Reconfigurable antenna can cover multiple working frequency bands and has different polarization modes and radiation pattern.Therefore,it has incomparable excellent characteristics compared with other conventional antennas and has potential application prospects in radar,satellite communication,wireless communication and other aspects.Reconfigurable dielectric resonant antenna which combines the advantages of dielectric resonant antenna and reconfigurable antenna will become a new research hotspot.However,as the radiating body of the dielectric resonator antenna is a non-metallic medium with high dielectric constant,the traditional reconfigurable technology based on changing the structure of the metal radiating body cannot be applied,which makes the realization of the reconfigurable dielectric resonator antenna extremely challenging.The thesis proposes the reconfigurable schemes electromagnetic characteristics of multiple modes,adjustable feeding network,parasitic element and combining MIMO on the basis of studying the factors of affecting and restricting the dielectric resonator antenna electromagnetic characteristics,explores the space of reconfigurable performance improvement,studies the frequency,polarization and pattern reconfigurable method in one or multiple parameter of the three dimensions.The research of this dissertation mainly includes the following four parts:Initially,the basic theory of dielectric resonance antenna,from mechanism and structure of the radiator and the feed network,are intensively studied.This thesis analyses the factors that influence the dielectric resonance antenna electromagnetic characteristics and put forward and verified the excellent performance of the new type radiator with conical structure and a new type of feeder based on stepped impedance resonator.On this basis,it explores the reconfigurable mechanism of dielectric resonant antenna.According to the characteristics of dielectric resonant antenna,the design idea of reconfigurable dielectric resonant antenna based on switchable working mode,adjustable feed network and optional parasitic element is proposed,and the diode characteristics and modeling method and setting method of bias circuit standardization in the electric reconfigurable control network are analyzed for improve the efficiency of design and simulation.The above lays a foundation for the follow-up research work of this paper.Secondly,in order to realize flexible and efficient control of dielectric resonant antenna working frequency,this dissertation proposes a method to reconstruct dielectric resonant antenna frequency based on an adjustable feed network based on an integrated resonator.The broadband rectangular dielectric resonant antenna with offset microstrip excitation is taken as the basic antenna unit.According to the different modes of the resonator acting on the microstrip feeder,three kinds of frequency reconfigurable dielectric resonant antennas are specifically designed:(1)Ultra-wideband,narrowband and band-notch discrete reconfigurable dielectric resonant antenna based on tapped resonator.(2)The discrete frequency and continuous tunable reconfigurable dielectric resonant antenna based on coupling resonator.It combines the odd-even mode theory of the multimode resonator and the ideas of pass filter and band-stop filter to realize the switching of multiple states.(3)Wideband integrated continuously adjustable narrowband dielectric resonant antenna based on path selection.Thirdly,the full polarization reconfigurable dielectric resonant antenna is studied.By controlling the relative positions of the gap and the dielectric resonator are different,different polarization characteristics are obtained.Based on the MIMO idea,the four-dielectric resonant antenna unit and feed are rationally arranged,and the polarization diversity dielectric resonant antenna with circular polarization and orthogonal linear polarization is realized.The polarization of dielectric resonant antenna is reconstructed by different ports.In addition,a polarization reconfigurable cylindrical dielectric resonant antenna excited by two probes based on Wilkinson power divider and optional phase shifter is proposed.On this basis,a polarization-pattern combined reconfigurable dielectric resonant antenna is realized by combining HEM mode with TM mode pattern diversity.Finally,the reconfiguration method of dielectric resonant antenna pattern based on parasitic element is proposed.The short-circuited parasitic element has the function of a director,combined with the omnidirectional radiation characteristics of cylindrical dielectric resonance antenna in TM01 mode,which make the maximum radiation direction of dielectric resonant antenna in horizontal plane regulated.Furthermore,a four beam reconfigurable dielectric resonant antenna based on drive parasitic element is proposed for low profile and high gain design.In this design,the antenna unit is based on the high TM02? mode,and the drive parasitic element changes the feed structure of the dielectric resonator antenna with the effect on field distribution enhanced.On this basis,the parasitic elements distributed on the ring are introduced,and the three-dimensional reconfigurable dielectric resonant antenna is realized.The dissertation focuses on the achieving electromagnetic characteristic reconstruction for dielectric resonator antenna.Based on analyzing the basic theory on dielectric resonator antenna,it explores the reconfigurable mechanism and train of thought of design.Design method and guide for frequency,polarization and pattern in one dimension or multiple dimensions are researched.And partial design are fabricated and tested for verification.This study provides a new technical approach for reconfigurable dielectric resonator antenna,and it will promote the research of dielectric resonator antenna. |
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