Design Of Narrow Beam Horizontal Scanning Antenna

In order to acquire the target quickly and accurately,it requires that the antenna has narrow beam and anti-interference performance in most detection and anti-collision radar systems.In order to realize the function of high resolution scanning in the horizontal plane,an antenna with a fan-beam is commonly used.There are many kinds of realizations.The main objective of this thesis is the metal plate antennas with a parabolic reflector.In these antennas,the two-dimensional reflective surfaces are designed with parabolic shapes.Two metal plates are used as the top and bottom plane of the reflector antenna.The end of the metal plate is open to realize the control of beam width in vertical direction.The horn feeder is placed between the plates to illuminate the parabolic reflector.The width of the aperture can realize the narrow beam in horizontal plane.The whole system is suitable for the mechanical scanning system.According to the location of the feed,the main contents of the paper are divided into the following parts:(1)Research on Forward-feed Parabolic Reflector Antenna.When adopting horizontal symmetrical configuration and placing the feed on the central axis of the reflection,which constitute the forward-feed parabolic reflector antenna.This antenna is the plane form of the three-dimensional parabolic antenna.But it has poor performance;the simulation results show that the main cause of the poor performance is relatively large blocking effect of the feed.(2)Research on Offset-feed Antenna and Sugar-shovel-type Antenna.When using asymmetric reflector,the feed is not in the reflective zones.Thus it can greatly reduce the block effect of the feed.When the structure is whole closed,it is named sugar-shovel-type antenna.Although the simulation results show that offset-feed design can solve the problem in forward-feed antenna.Its horizontal radiation pattern is dissymmetry due to the dissymmetry of the structure.(3)Research on Double Layer Forward-feed Antenna.Put forward a new type of double layer forward-feed parabolic reflector antenna.The feed and the reflector are under different isolation layers.This structure keeps the advantages of symmetric structure and symmetric radiation pattern,and solves the block effect of the feed.After the full wave simulated,optimized and designed,a real antenna is made.It was tested and the results verifiy the effectiveness of the design.