Study Of Monopulse Waveguide Slot Antenna

Waveguide slotted array antenna radiates outward by different slots on the surface,therefore this kind of aerial naturally has the characteristics of the compact structure and the light weight.As the same time,aperture distribution can be controlled by the slots,therefore the antenna is easier to achieve the requirements of low side lobes and high gain.Based on the advantages of the antenna in terms of structure and performance,this antenna is convenient to install on the missiles,warships,radars and other places with high structure requirements and complicated environment.This thesis completes the design and fabrication of a Ku band monopulse slotted waveguide array antenna.It is divided into four parts to elaborate.The first part starts from the theory of the monopulse slotted waveguide array antenna and introduces basic theory of the monopulse angle measurement and the structure of the monopulse feed network in the three-dimensional space.Converting the study of slot antenna into a dipole antenna uses the Barbiner principle.The theory of the radiation of the waveguide slot antenna is be deduced.The next step is to analyze the different type of slots on the surface of waveguide and deduce the equivalent circuit model corresponding to different gaps.The arrays are constitutive of different forms of slots and analyze their advantages and disadvantages.The second part finishes the design of the waveguide slotted array antenna.Taylor's synthesis is selected to calculate aperture distribution to determine the number of slots and the excitation distribution.The relationship between resonance conductance(resistance)and excitation distribution is deduced by converting the waveguide slot model into transmission line model.To consider the problem of the mutual coupling between the slots,5x5 small array and 5x6 small array are established respectively.The parameters of the radiation slots and coupling slots are extracted to obtain the relationship between resonance conductance(resistance)and slot position parameters.The design of antenna array is finished.The third part finishes the design of the monopulse feed network.A novel two-layer planar waveguide magic T which the E-arm and H-arm are connected through a coupling slots is designed by improving the traditional waveguide magic T.To finish the design of the feed network,three planar waveguide magic T and one H-T component are adopted.The fourth part finishes the manufacture of the antenna.The antenna model is built to simulate and error analysis and it is divided into five layers for processing.Finally the antenna is measured which the sidelobe level in the azimuth or elevation plane is less than-15 dB and null depth is more than 24 dB,The bandwidth of the VSWR is 1.5GHz,the measured results meet the requirement.