Research And Design Of The Airborne Antenna

Nowadays,drones are becoming more and more powerful.As a light,portable,and highly maneuverable equipment,they are increasingly used in military missions,agricultural production,smart logistics,and exploratory rescue.The airborne antenna undertakes the task of information interaction in the UAV system and is a vital module in the UAV communication system.The performance of the antenna directly determines the working quality of the entire communication system.Due to the complexity of the UAV’s functions,the body carries a variety of communication equipment and functional modules.Therefore,a large number of antennas used for electronic countermeasures,communications,navigation,radar and other functions are integrated on the UAV.In order to improve the UAV space utilization,the antenna module needs to achieve multi-frequency operation and have the characteristics of low wind drag to avoid affecting the flight experience of the aircraft.In addition,a variety of flight attitude changes are usually implemented according to requirements during work.In order to avoid polarization mismatch problems in communication,the airborne antenna also needs to have the characteristics of dualpolarization.Based on the application scenarios of unmanned aerial vehicles,this paper has carried out relevant research on airborne antennas.On the one hand,it conducts relevant investigations on the current research status of airborne antennas at home and abroad,and summarizes the characteristics and research directions of airborne antennas.On the other hand,according to the application conditions,relevant design,analysis and testing work was made for the three antennas.First,a dual-band omnidirectional airborne antenna is designed with low wind drag,which works in UHF and L-band.Realize the characteristics of horizontal omnidirectional coverage.The isolation between the two antenna elements is greater than 25dB,the maximum voltage standing wave ratio of UHF band(480MHz-630MHz)is 1.91,the maximum gain is 0dBi,and the gain variation of the pattern is less than 3dB;the maximum voltage standing wave ratio of L band(1429MHz-1710MHz)is 2.0,the maximum The gain is 2dBi,and the gain variation of the pattern is less than 3dB.Secondly,taking into account the polarization mismatch problem sometimes encountered in antenna information transmission and reception,a dual-polarized omnidirectional antenna working at 2.44GHz was designed,which uses a slot antenna to achieve horizontal polarization and vertical polarization is realized by the inverted F antenna with parasitic branches.The overall structure of the antenna realizes the omni-directional radiation characteristics of the horizontal/vertical polarization state in a small size,and the gain variation of the pattern of the two antenna elements is less than 3dB;by introducing the floor gap,the mutual coupling problem between the antenna elements is solved.The isolation between the two antenna elements is greater than 15dB.Finally,a broadening method of the bandwidth for airborne antennas is proposed.The characteristic Modes theory is introduced into the antenna design process,and a general design method for the antenna bandwidth is refined;and three proximity-fed sector antennas with different sector angles of 250°,275° and 293° are designed respectively.The relationship between fan angle and bandwidth is described.Finally,the antenna with a sector angle of 293° was fabricated and measured.Research shows that the antenna finally obtains a broadband of 530 MHz(35.3%),which achieves a broadening of the bandwidth;the gain of each frequency point in the working frequency band is above 6.5dBi.For the foreseeable future,drones will become indispensable and important equipment in human activities.With the improvement of science and technology,people will also put forward higher requirements for the performance of UAVs,and the research on airborne antennas will also be deeper and more challenging.