| At present,the modern wireless communications systems are developing rapidly,the conformal array antennas with performances of multi-beam radiation,omni-directional coverage attract more and more researchers' attentions.Combined with the technologies of conformal array antenna and beam forming,beam coverage in the horizontal and vertical dimension can be easily realized.At the same time,two orthogonal space dimensions of multi-input multi-output(MIMO)system is developed,3D MIMO performance is achieved and the capacity of communication system is greatly improved.In this paper,in order to analyze the array mutual coupling and realize omni-directional beam coverage,the antenna elements,the embattling of cylinder conformal array,the technology of beam-forming,the multi-way unequal power divider are studied.The main contents and results of the study as follows.1.Three kinds of antennas with the performances of broadband high-gain circular polarization are designed.To the first kind of antenna element,it was fed by a wide rectangular aperture coupling.The measurements show that the impedance bandwidth is about 32%,and the bandwidth of AR is about 20%.The gain of the antenna is lager than8.5 d B across the whole operating frequency band.To realize the broadband circular polarization characteristics,a double-Y-shape slot structure is adopted in the other two antenna elements.For one of them,the measurements show that,the-10 d B impedance bandwidth of the antenna is 32.7%,the 3 d B(AR)bandwidth is 20.7%,and the gain of the antenna is about 9 d B.For another one,by improving the structure of the prior ones,the performances of ultra wideband and high gain were realized.The measurements show that the impedance bandwidth is about 71.0%,the bandwidth of AR is about 49.8%,and the gain of the antenna is better than 8.5d B.Metal reflectors are placed under the feeding layer for generating unidirectional radiation and improving the gain of the three kinds of antennas.2.The embattling forms of cylinder conformal array is studied.By the reconfigurable technology,12 subarray are used to realized omni-directional multi-beam scanning.The formulas of the far field radiation pattern of the antenna array are also deduced.According to euler rotation transformation,the relationship of the global coordinates of cylindrical conformal array and array element local coordinate transformation are studied.3.Concerned with the problem of the mutual coupling of conformal array.In the first place,the mutual coupling coefficient matrix is deduced by the method of free incentivescattering,and the calculation formulas of the matrix are presented.In the second place,according to the active element pattern theory,the effects on the pattern by array mutual coupling is analyzed.4.The beam-forming technique of conformal array is studied.The main contents of the conformal array beam-forming are introduced in detail,including the core algorithm of TPA(team progress algorithm),shaded area calculation and beam forming.Based on the basis of standard team progress algorithm,an adaptive factor is proposed.So the optimal value can be found in the late running,and the progress strategy of its members can be improved.Then the adaptive team progress algorithm(A-TPA)is obtained.At last,the sub-array radiation patterns of the proposed cylindrical conformal array antenna are synthesized by the adaptive team progress algorithm(A-TPA).5.Broadband multi-way unequal power divider with large division ratio is designed based on the technique of T-shape stub.The structure of proposed cylindrical conformal array antenna is fabricated.In the microwave anechoic chamber,the power divider can be used for the feeding network in the measurement of radiation pattern of a beam-forming conformal array antenna.The measurements results that are well agreement with the simulation ones,which not only show the rationality of beam-forming algorithm for cylinder conformal array,but also indicating the validity of the proposed design strategies for the unequal power divider. |
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