| Satellite navigation system is one of the breakthrough achievements in the exploration of new technologies and new methods in the history of human navigation.However,because of the numerous electromagnetic interferences and deliberate interference from the enemies in the surrounding environment,the anti-jamming ability of satellite navigation systems has become a critical factor in effectiveness.Usually,the spatial adaptive anti-jamming technology of satellite navigation system is based on array antennas,but such anti-jamming antennas have a defect that the diameter of the antenna is large.Therefore,research on the miniaturization of navigation anti-jamming antennas has become a hot topic.This thesis introduced the development of anti-jamming antenna arrays.Based on the interference and superposition principle of electromagnetic waves,the characteristics of the array antennas are studied.At the same time,according to the microstrip antenna theory,the miniaturization design of the array antenna is studied.Its main tasks are:(1)The currently used navigation anti-jamming technology are compared,and the relevant theory of the array antenna is simply analyzed,the interference and superposition principle of electromagnetic waves are combined to analyze the far-field radiation characteristics of the array antenna.At the same time,the miniaturization technology of the microstrip antenna is studied,which provides a theoretical support for the miniaturization design of the microstrip antenna unit.With reference to the aforementioned theory,a rectangular circularly polarized microstrip patch antenna and a microstrip deformed monopole antenna are designed.Since satellites require sufficient gain for low antenna elevation angles,a widebeam circularly polarized microstrip antenna is designed using a rectangular microstrip patch-loaded metal-strip approach.The simulation results in a single feed rectangle resonant at 1.268 GHz.The half-power lobe width of the circularly polarized antenna reaches 156°.Then,the radiation mechanism of the monopole antenna is analyzed.The two bent and deformed monopole antennas are designed accroding the previously mentioned meandering technology,the resonant length was reduced to one-tenth of the wavelength,and the maximum radiation direction was at Theta =38°,the maximum gain reaches 2.6d B.(2)In the design of the antenna array,the differences and connections between the rotary and the translational layout methods are discussed,and the influence of the presence or absence of the center element on the antenna performance during the layout of the array elements is studied.Finally,using the above two kinds of antenna elements,a five-element heterogeneous array is formed according to a central element rotation layout,and its performance is analyzed.After being optimized,the s parameter is below-10 d B,the wide angle axis ratio is below 6 d B,and the elevation angle is greater than 25°,the array antenna gain is greater than-1d B,and the array size is reduced to one-fifth that of an ordinary array.(3)Since all the previous theories on navigation anti-jamming technology are based on isomorphic arrays of the same unit,they are not suitable for the anti-jamming technology of the heterogeneous arrays in This thesis.Therefore,the end of This thesis,The anti-jamming idea applying to heterogeneous arrays is briefly studied and specific design steps are elaborated. |
PDF Full Text Request