Research On Ka - Band Ultra - Wideband Tracker

With the development of radar technology of communication, whether between earth stationsand satellite communication, or communication between the satellite and satellite, requiretransmitting antenna and receiving antenna beam accurate alignment. If a deviation occurs, it willcause the gain is reduced, thus affecting the quality of the signal transmission. The researchershave been devoted to how to align the beam accurately, a good method is to use multi-modewaves work in waveguides, produce an error voltage, drive the antenna to track the target. Athome and abroad with a multi-mode tracker are based mainly TE21-mode and TM01-mode. Bycontrast TE21-mode easier to form a circular polarization, so most of the projects have adoptedthe TE21-mode coupler design antenna feed section.Reading a lot of related literature both at home and abroad, this paper introduces thebackground and significance of the radar system, and its history and current developmentresearch.By simply describes the characteristics of the microwave, leads to the Maxwell equations,the transmission theory of rectangular and cylindrical waveguide. Next, the basic principle of thedirectional coupler are described, directional coupler as the basis for in-depth theoretical study ofthe TE21mode coupler, the initial value is given according to the formula, and using HFSSsimulation software gives the corresponding graph. By optimizing the radius of the couplingholes and the spacing of the coupling holes, to enhance the performance of TE21-mode coupler,and gives a comprehensive evaluation.The microwave components used in today’s, using conical waveguide instead of cylindricalwaveguide, using a small opening angle of the conical waveguide as the main waveguide canbetter stimulate higher order modes. Such as TE21-mode, TM01-mode, in order to allow couplingbetween TE21-mode and TE10-mode is0dB, it must meet TE21-mode and TE10-mode have thesame phase constant, deputy also need to use a small opening angle of the rectangular waveguide,in such conditions, you can get high performance expectations. Value of the diameter of theconical waveguide has strict requirements, we should not only can ensure the TE11-mode fromthe main waveguide transmission, also should guarantee TE21-mode can be coupled, cutoffwavelength of TE21-mode is2.06R, cutoff wavelength of TM11-mode is1.64R, because operating bandwidth is very wide, we can’t avoid the high frequency of high order mode, we canonly try to reduce the amount of high order mode and the size of excitation. Through HFSSsimulation, you can verify the improved structure has feasibility.