Research Of Radiation Directivity On Sub-Array Of The Big Area Reflectarray

With the development of modern satellite-communication, the antennas which are suitable for satellite are being researched widely. Especially the reflectarrays have small size and broadband characteristics, which can be folded .But the shortcoming comes with the big-area application .it means the frequency and radiation directivity can not match well in the working frequency band .It is a hot topic to make frequency and radiation directivity match well . This incompatibility comes from 4 factors below:1) The limitation of patch working-frequency band2) The space among the elements3) The limitation of feed working-frequency band4) The phase shift of all elements of different locationIn this paper, the fractal patch, fractal array and multifacet reflectarrays are introduced and applied. With these concept and theory ,we can optimize the elements, the space and the space shift .then a big-area reflectarrays is used in the ka band, whose frequency and radiation directivity can match well .the design target is to design an antenna whose central frequency is 34GHz;its radiation directivity change slowly as the frequency change ;Its reflection coefficient is stable in the band. To prove the design thinking, We use the commercial software simulating, made the small size model which was tested. All these proved the design thinking of using fractal patch unit, planner fractal array and multifacet reflectarrays is a suitable method to match the frequency and the radiation directivity.