Research Of The TE21-Mode Coupler In Precision Tracking Antenna

There are technology progresses on precision tracking antenna during the past years. In the past, multi-horn feed was used in monopulse precision tracking antenna,now circular waveguide diffrentional mode feed is used.Compared with the precision tracking antenna that use multi-horn feed, precision tracking antenna that use circular waveguide diffrentional mode feed has similar tracking precision and has better balance between "sum mode" and "diffrentional mode".Diffrentional mode coupler is the key device in diffrentional mode precision tracking antenna.This paper introduces several diffrentional mode tracking methods,and gives the performance requirements for the diffrentional mode coupler by analyzing the whole antenna.Then it presents those coupling structures that can be used in TE21mode coupler and gives the comparision result. The coupled wave theory is introduced in detail, and the waveguide multi-mode multi-aperture coupler is also analysed thoroughly.It declares the condition under which energy can be fully coupled from one mode of line1to another mode of line2.It defines mode discrimination and gives basic analysis.It also gives the methods that can be used to enhance mode discrimination within fixed coupling area.It lists the design progress of TE21mode coupler.It compares several coupling distributions and finds out the better one.It also provides the individual hole coupling function,by which we can get the hole dimension. This paper presents a design of Ku band TE21mode coupler and gives the simulations results. The design method is confirmed and is also practicable for waveguide high order mode coupler design.