| High gain antennas with the capacity of precise multi-space coverage or dual/multi-band have been an inevitable trend in some fields where wireless communication presents the characteristics of high configuration,high load,high service demand and shortage of radio of spectral resources,and other fields in which fixed spot beam coverage or shaped-beam put forward new requirements for satellite communication antenna.Multi-beam or dual-band antenna bases on reflectarray has been the excellent candidate in terms of above-mentioned application background and there is not only application value but also scie ntific value for doing research in this field.In this paper,two array antenna and a feed horn are designed,which are a dual band circular polarized aperture-coupled transceiver reflectarray antenna,a bidirectional four-beam reflection/transmission array antenna optimized with genetic algorithm and a multifunctional completely inhomogeneous corrugations feed horn.In order to reduce the size of unit two annulus with different radius are employed as radiation patch and placed in the diagonal line of unit cell.The side length of the unit cell is half a wavelength at central frequency of lower band(19.6-21.2GHz)?In consideration of extending phase compensation range and improving the linearity of the phase curve aperture coupled structure is chosen for coup ling the electromagnetic energy received by the radiation patch to the short-ended microstrip delay line.The hierarchical structure enhances the space for arranging the delay-line thus resulting in the inter-band and cross-polarization isolation below-20 dB.Simulated results show that axial ratios are below 2 dB and directivities are above 25 dBi in both band.The aperture efficacies are 51% and 45% for two bands and the incident and reflection angle are both 10°.The posed bidirectional four-beam reflection/transmission array antenna are composed of Babinet units whose cross-pol component of reflection and transmission coefficient are equal,which guarantees the design of transceiver.Adoption of the genetic algorithm avoid the high level of side-lobes and deviation of beam direction which are very obvious in array designed by direct design method or alternating projection method.There are four beams in both the reflection and transmission side,totally eight beams,beam directions are ?=15°,±45°,?=90° or 270° depends on ?.Simulated results show that the level of sidelobe are below 13.1 dB,the average directivity is 13.2 dBi,and the summation of maximal deviation of beam direction is 7.5°.The design procedure of the posed completely inhomogeneous corrugations feed horn combines the accurate and efficient modal match method and genetic algorithm and divide the total process into two parts: optimization of modal content on aperture and optimization of horn structure.The completely inhomogeneous corruga ted structure greatly improves the design freedom of the horn and improves the overall completeness of goals.Simulated results indicate that The reflection coefficients of the horn are less than-22 dB for both band,the level of the first side lobe is-32 dB and-25.6 dB for two band,and the aperture efficiency at the center frequency reaches 75% and 56%,respectively.The simulation results of the above two kinds of array antennas have reached the expected targets and can be applied in the fields of satellite communication,electronic countermeasures and other wireless communication.The corrugated horn is measured with Agilent N5227 A vector network analyzer,and the test results are in good agreement with the simulation,which proves the feasibility and superiority of the distribution design scheme based on genetic algorithm,which can be used as the primary feed source for various reflectors and array antennas. |
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