| Combined of the Bei Dou navigation system and the terrain contour matching system,the integrated navigation can be improved to ensure that the system can continue to work stably and reliably in harsh environments.For missiles,their space is limited,and they are in highspeed motion and rotation during flight.Therefore,the missile-mounted integrated navigation antenna is required not only to have dual-band dual-polarization performance to save space,but also to provide omni-directional radiation coverage to satisfy the signal stability when the attitude is changed,and to be conformal to the missile to meet aerodynamic performance at the same time.According to the application background,this paper mainly studies the design of dual-band dual-polarization conformal array antennas.The antennas operate in the B3 band of the Beidou system and the C-band of the radio altimeter antenna in the terrain matching system.In addition,circular polarization and linear polarization are realized in the B3 band and the C band,respectively.The array antenna is conformal to the projectile and its directional pattern achieves omnidirectional coverage in the azimuth plane.This paper focuses on the dual-band,dual-polarization,miniaturization and conformal problems of antennas.Three types of dual-band dual-polarization antennas are proposed,including combination nesting,slot-loaded and stacked structures.And each form of antenna element is used to form a corresponding conformal array antenna.Through the results of the given reflection coefficients,axis ratios,directional patterns,et al.,it is shown that the designed array antennas satisfy the design requirements.Firstly,a combination nesting form of dual-band dual-polarization conformal array antenna is designed.A new structure of combination nesting antenna is proposed with the high frequency patch placed in the middle of the square ring of the low frequency patch to achieve dual-band and dual-polarization.It is analyzed that the addition of metal posts between two patches can reduce the influence between patches and achieve better radiation performances.In addition,a method of adjusting the square patch in the conformal structure to the rectangular patch is proposed,which can improve the circular polarization performance at low frequency.The designed conformal antenna has good dual-band dual-polarization and omnidirectional radiation performance.Secondly,the structures of slot-loaded dual-band dual-polarization conformal array antennas are designed.This form of antenna uses the loading slots to introduce another operating frequency.By comparing the results of the two antennas fed by the single port and the dual ports respectively,it is concluded that the antenna performances of the dual-port feed are more excellent,and thus the dual-port fed slot-loaded antennas are used to form the conformal array antenna.Simulated and analyzed the array antenna of two conformal methods of embedded and curved,the results show that the two conformal methods basically meet the requirements of dual-band dual-polarization and omnidirectional radiation.Finally,a dual-layer structure with single-feed is proposed to achieve dual-band dualpolarization of the antenna.The dual-layer antenna uses two substrates with different relative permittivity.The upper patch operates at a high frequency band,and the lower patch operates at a low frequency band.The feed probe is connected to the upper patch through the drill hole of the lower patch.The advantage of this type of antenna over the above two forms is that the high-frequency patch and the low-frequency patch work independently and the highfrequency patch has a large adjustable range,which is convenient for adjustment.The final designed conformal array antenna has good dual-band dual-polarization performance and omnidirectional radiation in the azimuth plane. |
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