| In the research of smart antennas,adaptive anti-jamming technology has an important position,because in today's increasingly complex electromagnetic environment,it can effectively suppress the influence of interference and improve communication quality.UHF communication is widely used in the military field,and it is also subject to many human interferences imposed by the enemy.Therefore,improving the anti-interference ability of UHF communication can increase the advantage on the battlefield.In this paper,the theory of Adaptive Anti-jamming Technology in spatial domain is studied,and combines the antenna array with the adaptive anti-interference algorithm to improve the anti-interference ability of UHF communication.Firstly,the design of the array antenna is carried out.According to the requirements of the anti-interference function,the number of units of the array antenna is determined to be eight,and then the array form is determined to be a uniform circular array.According to the working bandwidth of 2.3 octave,the sleeve monopole antenna and the bi-conical antenna with horizontal omnidirectional radiation in the azimuth plane are designed.And the bi-conical antenna with a small lateral size(0.07?ma x)and a large gain is selected as the antenna unit.It is determined that the radius of the ring is0.33?ma x,and an 8-element uniform circular array is formed in the azimuth plane.Finally,the VSWR of the antenna array is below 2,and the gain can reach 7dBi or more when the array beam is omnidirectionally scanned in the azimuth plane.For the airspace adaptive anti-jamming technology,the core is the control and calculation of the received array signal by the algorithm.The anti-jamming function is realized by the SMI zero-setting algorithm with fast operation speed,which makes the formed pattern produce deep zero-pit in the direction of interference.The adaptation is embodied in that when the angle of interference signal incident on the array changes,the algorithm also needs to be adjusted in real time to make the angle of null in the pattern change accordingly,and the adaptive MUSIC algorithm is used to ensure the real-time detection of the direction of the interference signal.In addition,the new algorithm combines the low sidelobe synthesis technology.The final algorithm improves the main lobe gain and the low sidelobe,and further improves the anti-jamming performance while realizing adaptive anti-jamming.Because the algorithm processes the signals received by the antenna array,the mutual coupling between the array elements will affect the direction of the unit,which will change the signal received by the array,thus affecting the effect of the algorithm in practical applications.In this paper,the decoupling matrix of the array is solved by the method of element pattern reconstruction,and then the decoupling matrix of the whole frequency band is obtained by the cubic Hermite interpolation method.The decoupling matrix is applied to the algorithm,and the signal received by the array is modified to eliminate the influence on the algorithm.When the final algorithm is combined with the array,the suppression of interference signal in the frequency band is more than 80 dB. |
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