Analysis Of Monopulse Antenna For Communication

Since the development of monopulse reflector antenna up to now,the development of monopulse antenna has risen to a new height due to the change of construction from multi-horn to single-horn multimode.Monopulse single-horn multimode antenna uses high order mode in circular waveguide as differential mode to realize self-tracking.It not only has high tracking accuracy,but also can have better balance between sum mode and differential mode.In this paper,the research of tracking technology of monopulse reflector antenna is presented,including TE21 mode coupler,difference network,circular polarization,corrugated horn and OMT.Each device is designed independently,and then the whole feed system is combined to simulate.The main contents are as follows:1.A TE21 mode coupler is designed.In the design of TE21 mode coupler,the circular waveguide is chosen as the main waveguide and the secondary waveguide is a rectangular waveguide.The energy of the TE21 mode of the main waveguide is converted to the energy of the TE10 mode in the secondary waveguide by opening 32 holes in their common walls.In order to realize the strong coupling as much as possible,the size of the coupling holes use weighted Bessel distribution,and the distance between the holes is 1/4 waveguide wavelength.The modeling and simulation of TE21 mode coupler in HFSS can realize the coupling loss of TE21 mode lower than 0.3d B,and the suppression degree of TE11 mode is less than-45 d B.2.A difference network is designed.Based on the characteristics of the power combination of ET and HT,a difference network is built.The TE21 mode and its degenerate mode are synthesized independently,and then a path difference of 90 °phase difference is given to them.Two kinds of polarization which represents left-hand difference and right-hand difference signal are produced after passing through a magic T,and then realize differential mode tracking.Finally,the simulation results in HFSS show that the transmission loss from each input port to the differential signal outlet is within 0.06 d B.3.The other devices in the feed are simulated and designed.The circular polarizer uses metal diaphragm as phase shifting element and uses square waveguide and circular waveguide to design.Their performance are compared and the better one is chosen to use.Based on the design experience of some scholars,the OMT in the form of square waveguide and corrugated horn are designed.Finally,all the devices are connected by transition sections,and the feed system is simulated.The results show that the matching and radiation characteristics are better.