| Satellite communication has many advantages,such as large communication capacity,wide coverage and good transmission quality.It has become a very important method of communication at present.As a form of satellite communication ground station antenna,mobile communication antenna has also become a hot spot of current scientific and technological research.As a kind of mobile communication antenna,panel antenna has many advantages such as high efficiency,small volume,low profile and easy integration and so on.It has also been deeply studied and widely used in the antenna field.In this paper,according to the research needs,the common-aperture dual-polarized panel antennas with different bands are studied and analyzed in depth.Firstly,the form and number of array antenna elements are evaluated according to the requirements of key performance indicators and size requirements.Secondly,we choose and design the array elements.The square waveguide step horn antenna with metal cross grids is selected and used as basic unit.The metal cross grids make the radiation electric field of the horn port more uniform,and also solve the problem of high frequency grating lobes.The element and array design method are discussed.Ku band dual-band dual-circularly-polarized panel antenna,a low side-lobe dual-band dual-polarized panel antenna,Ka band dual-frequency dual-circular-polarized panel antenna are designed,dual polarized parallel plate waveguide antenna.For different panel antennas,the basic research methods and results analysis in this paper.The design of square waveguide step horn antenna,Ortho-mode transducer,power divider network,waveguide directional coupler,diplexer and feed network is summarized and analyzed.The Ku band dual-frequency dual-circular-polarized antenna contains square waveguide horn antenna unit,Ortho-mode transducer,upper and lower two levels of power divider network and feed network.The feed network consists of high and low frequency diplexers and directional mode couplers.In this paper,the design and simulation of the above devices are discussed,and the design methods and simulation results are analyzed in detail.The overall bandwidth of the dual-band dual-circularly polarized panel antenna in Ku band is 41%,the center-frequency ratio of high-low frequency is 1.46,and the gain of high-low frequency is more than 32 d Bic.The Ku band dual-frequency dual-circular polarized low side-lobe panel antenna is an in-depth exploration of the panel antenna with equal amplitude distribution.This chapter introduces several design methods of low side-lobe antennas,introduces the design method of unequal power divider,and verifies the design method of the unequal power divider.The basic design scheme of dual-band dual-circularpolarized low side-lobe array antenna is given.The maximum side-lobe level of each frequency point in the two dimensions of the antenna is-18.04 d B.The bandwidth of the antenna is the same as that of the Ku band panel antenna described in the previous section,and the shortcomings of the antenna are summarized and analyzed.The Ka band common-aperture dual-frequency dual-circularly-polarized panel antenna contains the same device as the Ku band antenna,and the array form is 8×8 square array.The difference is that the high and low frequency waveguide phase shifter is introduced on the feed network.Because the overall relative bandwidth of Ka-band antenna is 45%,the relative bandwidth of high and low frequency is 5.3% and 7.8% respectively,which is larger than of Ku band penal antenna,the phase difference required to synthesize the circularly polarized wave is relatively poor in the corresponding frequency band,resulting worse axial ratio in the overall.After introducing the waveguide phase shifter,the phase imbalance has been greatly improved,and the axial ratio of the antenna has also been improved.The axis ratio was improved from less than 2.6d B to less than 1.1d B in corresponding bandwidth.The design of dual-polarized antenna based on parallel plate waveguide is an extension of low profile dual-polarized plate antenna.The profile height of the dual-polarized parallel plate waveguide antenna designed in this chapter is 1.3 times of the wavelength,which is lower than the 4.8 times of the profile height of the dual-polarized plate waveguide antenna.The dual-polarized parallel plate waveguide antenna is composed of power division network,parallel plate waveguide,metal cavity and radiation slot.Compared with the plate antenna studied in the front chapter,the dual-polarized parallel plate waveguide antenna has some disadvantages in bandwidth,but its structure is simple and its processing cost is low. |
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