Research On Miniaturization Of Missile Borne Antenna For Trajectory Measurement

The trajectory measurement missile-borne antenna is an antenna formed to meet the need of real-time testing of the technical parameters of the projectile in flight during the research and development of the precision guided ammunition,which is usually composed of a receiving antenna and a transmitting antenna.It is only a test equipment for the design of the ballistic weapons and the precision guided weapons.So this type of missile borne antenna must be in small size,light weight,must not occupy the valuable space and launch weight.Meanwhile it must have high mechanical strength and the ability to work well in harsh conditions,and it mustn’t affect the aerodynamic shape and flight performance of the projectile.According to the requirements of real-time trajectory measurement,this thesis designes two transmitting antennas and receiving antennas which can meet the requirements of high mechanical strength without affecting the aerodynamic shape of the projectile through the miniaturization of the antenna.The Main research contents and creative points in the thesis are summarized as follows:1.By using parallel double transmission line which can providing differential feed,a 180 degree phase difference is introduced,then the first level of the power divider is omitted.By the introduction of the virtual ground,the two second level power dividers are printed on both sides of the dielectric substrate.The radiator adopts quadrifilar helix antenna of which the planar structure greatly reduces the overall height of the antenna.The miniaturization of the antenna on the whole is achieved by attaining the planar structure radiator and the miniaturized feed network.2.To further reduce the overall height of the antenna,the metal probes are replaced by the apertures,and the signal is transmitted to the radiator from the feed network through the aperture coupled feed.Meanwhile it also solves the problems of metal probe assembly,such as inconvenient assembly,easy bending and uneasy welding,so as to further achieve the miniaturization and simplification of the antenna.3.The metal body of the projectile is equivalent to an infinite metal surface according to the principle of mirror image,the electric field generated by the other side arms of the microstrip quasi Yagi antenna can be equivalent to be generated by the mirror image of one side arms of the microstrip quasi Yagi,then the other side arms of the microstrip quasi Yagi antenna can be omitted which greatly reduces the size of the radiator,so as to further achieve the miniaturization of the antenna.4.The circular polarization characteristic of the array unit is obtained by rotating the patch,and the whole antenna is conformed with the projectile in the annular slot which is fixed to the surface of the projectile.By using the aperture coupled feed,the feed network is designed to be placed below the radiator,so that the curved conformal surface size of the whole antenna is reduced to half of the original,achieving the purpose of miniaturization.