| With the development of radio technology,antenna,as an important component of radio equipment,is widely used in radar,communication,navigation and other fields.Due to the special working conditions of radar system and airborne radio system,Due to the special working conditions of military radar system and airborne navigation and communication system,the antennas involved in them have also attracted much attention and become an important research direction in antenna field at home and abroad.In view of the special requirements of the above systems for antennas,this thesis studies and designs low sidelobe array antennas and airborne multi-mode antennas based on relevant theories and scientific research projects.The main works are as follows:1.Based on the research of low sidelobe array antenna,a lightweight low sidelobe array antenna working in X-band is designed.Firstly,according to the antenna gain,beam width,peripheral size and other indicators,the spacing and number of the array elements are determined.The sidelobe level and the feasibility of the feeding network are comprehensively analyzed,and the Taylor synthesis method is selected to calculate the excitation amplitude and phase distribution of each elements.Based on the consideration of bandwidth and integration,a broadband printed dipole antenna is designed.Then,based on the array excitation distribution,the topology structure of feed network is determined.Then,based on the array excitation distribution,the topology structure of feed network is determined,and a one-point thirty-two suspended stripline power division network is designed with Wilkinson power divider.The combination of electromagnetic simulation with HFSS software and calculation with MATLAB software verifies that the network has good impedance matching and transmission characteristics.Finally,the array is simulated and optimized,and the results showed that: VSWR is less than 1.6,the gain is greater than23.5d B in band,the sidelobe level is less than-25.8d B,and the weight of single chip is 3.6kg,which meet the requirements of the index.2.After research on airborne multimode antennas airborne multi-mode antenna,an airborne multi-mode antenna which is working in UHF satcom mode,Tiantong mode,Tianxing mode and Beidou navigation mode is designed.Firstly,according to the working frequency band of each mode,the antenna elements of each functional distribution pair are designed by splitting the functions of the antenna elements.Circularly polarized microstrip antenna with laminated structure is selected in the Tiantong/Tianlian mode,circularly polarized wave is synthesized by UHF satcom antenna in the way of four feeds,and circularly polarized microstrip antenna with double feeds is adopted in Beidou navigation mode.Then,on the basis of anti-jamming theory,combined with the design of antenna elements in each mode and the dimension of antenna,the anti-jamming array form and space layout are determined.The results show that the gain of array is 12.32 d B and the radiation characteristics are good in the range of ±36°.The gain of the Beidou S-band four-element "rotary" circular array is 9.85 d B at intermediate frequency,and the axial ratio is less than6 d B in the range of 20°～90° elevation.UHF satcom antenna,Beidou L-band transmitting antenna and Beidou B2 b receiving antenna still maintain good performance after installation,and meet the index requirements. |
PDF Full Text Request