| Due to the continuous upgrading and increasing multi-functionality of electronic equipment in the fields of modern radar,electronic countermeasures,wireless communication,radio astronomy and so on have put increasing demands on antennas,the miniaturized ultra-wideband antenna has become one of the important research topics in the field of antennas at home and abroad.In this paper,the miniaturization techniques of two kinds of ultra-wideband antennas,such as planar spiral antenna and Vivaldi antenna,are deeply studied,and miniaturized,ultra-wideband planar spiral antennas and Vivaldi antennas are designed respectively.The specific content and work of this article includes:1.Based on the in-depth study of the planar spiral antenna miniaturization technology,a miniaturized planar spiral antenna operating at 218GHz is designed.A traditional Archimedes spiral antenna with self-complementary characteristics is used as a radiating element.Because its size is too large to meet the requirements of the index,resistance loading is performed on its spiral arm to reduce the lateral dimension.The initial length of the exponential gradient balun as the feed structure is?max/2,which causes the profile of the antenna is too large.We reduce the length to?max/4 and optimize other parameters to lower the profile height.In order to make the antenna have unidirectional radiation characteristics,a metal reflective cavity is designed,and the absorbing material is filled in the cavity to ensure the ultra-wideband characteristics of the antenna.The three-dimensional size of the antenna is 39mm*39mm*32.2mm,which is about 42%smaller than conventional Archimedes spiral antenna.The VSWR is less than 2.5 in the whole band,no beam splitting in radiation pattern,and the gain is-8.2dB?2GHz?6dB?18GHz?.The test result are basically consistent with the simulation result.2.Based on the in-depth study of Vivaldi antenna miniaturization technology,a miniaturized Vivaldi antenna operating at 26GHz is designed.Based on the traditional Vivaldi antenna,the influence of its key parameters on the performance of the antenna is studied.It is found that the antenna has poor directivity at low frequencies.It is analyzed that due to the short electrical length of the antenna.Therefore,a corrugated edge structure is added to the antenna metal radiating arm to ensure that the physical length of the antenna is constant,the effective length of the antenna is increased,and the directionality of the low frequency is improved.The antenna size is 70mm*43.8mm*1mm,the gain is not significantly reduced on the basis of miniaturization,and has good impedance characteristics and pattern characteristics.3.Based on the research of 26GHz Vivaldi antenna,a Vivaldi antenna working at 618GHz was designed.In addition to adding a corrugated edge structure to the metal radiating arm,this antenna adds a parasitic patch to the opening of the index slot to further increase the antenna gain.The antenna size is 34mm*36.5mm*1mm,and it has good impedance characteristics and radiation characteristics in the working frequency band.4.A dual-polarized Vivaldi antenna operating at 218GHz is designed.The two different Vivaldi antennas described above are placed orthogonally to form a dual-polarized structure,one of which operates at 2 to 6GHz and the other operates at 6 to 18GHz.The three-dimensional size of the dual-polarized antenna is 80mm*80mm*45mm?with floor?.The VSWR is less than 2.5 in the whole band,the pattern characteristics are good,and the gain is 6.05dB?2GHz?12.78dB?18GHz?.The test result are basically consistent with the simulation result. |
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