Study On Low-sidelobe And Circularly-polarized Wideband Dielectric Resonator Antenna Array

Nowadays,the rapid development of modern wireless communicaitons,satellite communication and navigation,and radar systems damand for advanced antennas in terms of wide bandwidth,polarized performance and low loss.With the development of radio engineering,single antenna can not meet the requirement in some particular situations due to a lower antenna gain and bad directivity.So,applications of antenna array can show a great value.Therefore,several innovative designs on low-sidelobe-level?SLL?wideband dielectric resonator antenna arrays?DRAAs?and circularly-polarized?CP?wideband DRAAs are proposed.Moreover,the corresponding experimental demonstrations are accomplished.Three main subjects are included in this thesis:Firstly,a C/X band series-fed low-sidelobe-level and wideband DRAA with slot windows and reflector is presented.In our design,the TM mode in the rectangular dielectric resonator is studied,and the structure of the unequal-amplitude series feeding network is analysed and optimized.The measured results show that,the proposed DRAA has an impedance bandwidth of 38.1%?6.72⁹.88 GHz?and a-20-dB SLL bandwidth of 6.82%?7.22⁷.73 GHz?.The measured highest antenna gain and lowest SLL of the proposed DRAA is 15.7 dBi?at 7.4 GHz?and-23.01 dB?at 7.54 GHz?,respectively.Compared with the performances of other proposed DRAAs,the bandwidth and SLL in our design are in the leading domestic level.Secondly,two low-sidelobe-level and wideband DRAAs for 60 GHz millimeter wave communications are presented.In two designs,the hybrid-radiation structure and perforated rectangular DRA are used to enhance the impedance bandwidth of the array element DRA,and U-shaped substrate and dual-layered substrate are used to guarantee the radiation patterns of DRAAs.The simulated impedance bandwidths of two DRAAs are both wider than 36%,and the lowset SLL are both lower than-27dB.Over the frequency band from 57 to 66 GHz,the gains of two DRAAs are both higher than 13 dBi.All these performances mentioned above in our design can meet the IEEE 802.15 and ECMA 384 standards in the 60 GHz wireless communication systems.Thirdly,two designs of CP DRAA with fractal cross-slot-coupled array element DRA are proposed.According to the measured results,the proposed CP wideband DRAA has an effective axial ratio?AR?bandwidth(S₁₁<-10 dB and AR<3 dB)of38.3%?6.06⁸.93 GHz?,and the peak left-handed circularly-polarized gain across the effective AR bandwidth is 12.17 dBi.Performaces of this DRAA is in the leading domestic level compared to others proposed CP wideband DRAAs.Besides the CP wideband DRAA,a design of CP low-sidelobe-level DRAA is also proposed,whose measured effective AR bandwidth is of 12.4%?6.58⁷.45 GHz?,and across the effective AR bandwidth a-15-dB SLL bandwidth of 9.97%?6.67⁷.37 GHz?can alos be achieved.According to other presented workings,few designs of CP low-sidelobe-level DRAAs are fabricated and measured until now.