| With the increasing demand for multi-functional integration and miniaturization of wireless communication equipment,high frequency antennas are developing towards multi-band and ultra-wideband technology.In addition,the increasingly scarce spectrum resources have promoted the research of antennas working in extremely high frequency bands.Based on the above requirements,this paper carries out the following work:1)A three-layer electromagnetic band gap?EBG?structure with controllable band gap is proposed.Based on this structure,a dual-frequency EBG planar printed antenna working at 3.95 GHz and 9.9 GHz is designed.The antenna can be used in civil wireless communication equipment.Combining EBG structure in antenna can achieve to suppress surface wave,reduce backward radiation and improve antenna gain.The single band gap generated by traditional EBG structure cannot satisfy the dual-band antenna with large working band spacing.Therefore,the realization of multi-band EBG structure is a difficult problem to be solved in the design of multi-band EBG antenna.In this paper,a three-layer EBG structure composed of slotted hexagonal metal patch,square metal patch and metal grounding surface is designed.By changing the size of the two patches,the EBG structure can be controlled to generate multiple band gaps working in different frequency bands,thus realizing the miniaturization and multi-band design of the EBG structure.The measured antenna operates at 3.85 GHz and 9.7 GHz at the center frequency.When the forward transmission coefficient S21<40 dB,the frequency range of the two band gaps are 3.71-3.96 GHz?5.3%?and 9.66-9.78 GHz?1.2%?.This structure reduces the back lobe radiation of the antenna at low frequency point by 20.89%and increases the gain at high frequency point by 25.7%.?2?In order to solve the problem that the processing errors of miniaturized and ultra-wideband Vivaldi antenna?3.1-10.6 GHz?easily lead to the instability of antenna impedance matching,based on the actual processing error values given by the manufacturer,the sensitive radiation structure and feed of the original Vivaldi antenna designed by the research group are further analyzed and processed,and a new type of antenna based on electricity is proposed.The magnetic simulation software HFSS improves the structure design of antenna radiation patch,changes the structure of antenna radiation patch,and compares the simulation results with the actual processing results.Finally,the main structural parameters affecting the performance of Vivaldi antenna are determined.The improved antenna bandwidth meets the design requirements and has more stable radiation performance.The antenna can be used in astronomical observation equipment.?3?For the application of Foreign Object Debris?FOD?radar,a 94 GHz extremely high frequency dual pyramidal horn antenna is designed in this paper.The antenna is fed by waveguide power divider.On the basis of traditional T-junction power divider,the impedance matching of power divider is improved by introducing wedge groove and trapezoidal tapered output port(S11<30 dB is realized in working frequency band).At the same time,the antenna designed in this paper uses pyramidal horn antenna with better directionality and higher gain,based on the application requirement that the half-power beam is not less than 10 degrees and the detection distance is more than 5 meters.In the integrated design of antenna and power divider,180°conversion of output phase is realized by introducing 1/2 wavelength waveguide tube,which makes the two ports have the same phase of output electromagnetic wave and 90 waveguide elbow,which makes the antenna installed at the two output ports of T-type power divider face to the same side,and 3D printing technology is used to process the antenna and power divider in an integrated way.The experimental data show that the radar system can successfully locate the position of triangular corner reflector within 10 m,which proves the effectiveness of the designed antenna. |
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