| With the development of science and technology,the application of wireless communication technology has been integrated into all aspects of people's life.As an important device for transmitting and receiving radio waves,the structure and performance of antenna directly affect the quality of the whole wireless communication system,the same as aircraft antenna.Due to the increasing functions of various aircraft and the increasing amount of information and data transmitted,higher requirements are put forward for airborne communication system,which makes miniaturization,low profile,broad Band and other key technologies become the research focus of airborne antenna.The research work of miniaturization airborne antenna can be divided into three parts:1)A dual band common aperture airborne knife-edge antenna is designed,which takes into account both low-frequency ultrashort wave communication and high-frequency 5G communication.Based on the monopole antenna,the matching circuit is loaded to realize VHF(108 MHz?174 MHz)ultrashort wave communication,and then the butterfly dipole antenna is embedded in the monopole antenna to realize UHF(2515 MHz?2675 MHz)5G communication.Combining the two antennas by coplanar embedding can improve the space utilization of the body surface and reduce the number of antennas.Finally,the size of the designed antenna is 0.089?× 0.05?(? is the center frequency wavelength),which realizes the miniaturization of the antenna.The simulation results show that the antenna low frequency gain is greater than-7.7 dBi,high frequency gain is greater than 9.1 dBi,the out-of-roundness of horizontal pattern is less than 0.3 dB,and the radiation performance meets the omnidirectional requirements.2)On the basis of the traditional Vivaldi antenna,the cross slot is loaded along the edge of the radiation slot line and the Y-slot is etched on the edge of the antenna to extend the current flow path on the patch and expand the low frequency bandwidth,so as to realize the miniaturization of the antenna.Then,the front end of the antenna is loaded with a seeker structure to improve the gain of the antenna.By comparing the simulation results,the Vivaldi antenna with Y-slot and seeker structure is selected for processing and measurement.The measured bandwidth of the antenna is greater than 6 times the frequency,and the gain value can reach 8 dBi.The polarization mode is vertical linear polarization,and the tested results of those fabricated circuits are well agree with the simulated ones.3)A concealed buried airborne array antenna is designed.The array antenna is placed in an buried cavity in the belly of the aircraft and covered with a wave transparent composite material which is completely conformal to the aircraft body.It not only does not affect the radiation performance of the antenna,but also solves the problem that the aerodynamic resistance of the external airborne antenna affects the sensitivity of the aircraft at high speed.By analyzing the simulation data,it can be seen that the buried antenna has little influence on the radiation performance,the average gain is only reduced by 0.9 dB.The array antenna with 5×16 elements is placed in the inner cavity.The maximum gain of the array antenna in L and S full frequency band(1 GHz?2 GHz)is 25.9 dBi.The cross polarization is below-30 dB,the sidelobe level is below-21.8 dB,and the beam scanning angle can reach ±30°with good scanning performance. |
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