Analysis And Synthesis Study Of Conformal Phased Antenna Array And Experiment

As the more general phased array form, conformal phased array (CPA) is theextension and development of the concept for planar phased array. The antennaelements of CPA being arranged on a platform surface not only expands the aperturearea of array and beam scan range, but also is good for the design ofaerodynamic-stealthy shape, which overcomes the inherent drawback of planar arrayand fulfill the development need of the modern electronic system. This paper focus onthe antenna array of CPA that is conformal antenna array (CAA), and make the theoryand experiment research in the accurate analysis of microstrip CAA, the analysis andsynthesis of array, the analysis and calibration for mutual coupling, the analysis andoptimization for polarization, and the design of the CPA. The contents list as follows:Firstly, the accurate numerical analysis of microstrip CAA is researched. Based onthe deduced volume-surface integral equation (VSIE), the precorrected-fast Fouriertransform (P-FFT) method and its application in radiation problem for CAA is studied.Besides, aim at coaxial probe feed conformal microstrip antenna, the “long coaxial feedmodel” is proposed, which can improve the precision of calculation for the radiationfield and S parameter, efficiently. Meanwhile, the characters of isolated conformalmicrostrip antenna, the conformal microstrip antenna in CAA, and the whole CAA areanalyzed by P-FFT method, successfully.Secondly, aim at the synthesis of CAA for single polarization element, theimproved aperture projection method (IAPM) is proposed, which enhance the ability ofsynthesizing large angle scan beam with low sidelobe. Meanwhile, the enhancedalternating projections method (EAPM) is proposed, and its convergence speed isaccelerated obviously compare with the traditional alternating projections method.What’s more, the precondition-enhanced alternating projections method (P-EAPM) isproposed by combining IAPM with EAPM. In P-EAPM, the element excitationsachieved by IAPM are regard as the initial value for EAPM to do further optimization,which could avoid the algorithm trapping in local optimum effectively.Thirdly, aim at the analysis and calibration for mutual coupling of CAA, themathematic model for single polarization CAA is built. The mutual coupling analysismethod based on the active element pattern is improved, besides the concepts of the“structure mode mutual coupling” and the “antenna mode mutual coupling” areproposed. Meanwhile, the effective calibration techniques are proposed for two kind ofmutual coupling. And the mutual coupling of the CAA, in which the elements are notterminated matched loads, is calibrated.Fourthly, for the purpose of synthesizing power pattern for single polarizationCAA, the adaptive dynamic meta particle swarm optimization (ADMPSO) is proposed. In ADMPSO, the dominated subgroup and nondominated subgroup are defined on thebasis of traditional meta particle swarm. Meanwhile, the adaptive dynamic modulatingfor multiple-subgroup is realized by introducing the downsizing of nondominatedsubgroup, the dominated subgroup expansion, and the updating for the adaptive inertiaweights, which improve the optimization performance of ADMPSO. Furthermore, theADMPSO algorithm is applied to synthesizing3D pattern and multiple-pattern inmicrostrip CAA, respectively.Fifthly, for the purpose of power pattern synthesis for single polarization CAAwith the excitations restricted, the improved multi-objective particle swarm optimization(IMOPSO) algorithm is proposed. By applying IMOPSO, the original problem can betransformed into the multi-objective optimization problem, in which the excitationoptimization and power pattern synthesis are considered at the same time. Byintroducing the particle focused distance selection, the nondominated solution setcutting, and the new particles copy mechanism, the performance of IMOPSO isimproved significantly, compare with traditional MOPSO algorithm. Moreover, the setof power patterns with different excitation restriction for microstrip CAA is achieved byIMOPSO, which offer the valuable reference for designing feed strategy of CPA.Sixthly, aim at the synthesis of full polarization conformal antenna array (FPCAA),the mathematic model of FPCAA which employs dual polarized antennas as radiators isbuilt, with the mutual coupling analysis and calibration techniques for FPCAA proposed.Meanwhile, based on the introduced “complete orthogonal polarization bases” concept，the generalized improved aperture projection method (GIAPM) and generalizedenhanced alternating projections method (GEAPM) are proposed forpattern-polarization synthesis of FPCAA. What’s more, by building thepattern-polarization fitness function, the ADMPSO is introduced to synthesize FPCAAwith mutual coupling considered.Lastly, based on the theory research of CAA described above, the transmit digitalbeam-forming full polarization conformal phased array (TDBF-FPCPA) is designed andmanufactured, with the corresponding experiments done. The cylinder CAA of theTDBF-FPCPA employs the fabricated new dual polarized stacked microstrip antennasas radiators, and the full polarization element pattern of every element is measured bybuilt vector pattern measurement system. The multi-channel digital transmit module ofthe TDBF-FPCPA is based on the direct digital frequency synthesis (DDS), and it cancontrol the amplitude and phase of signal in every channel accurately. Meanwhile, thelarge dynamic amplitude control is gotten by the RF numerical control attenuator.Furthermore, the TDBF-FPCPA transmits several kinds of shaped pattern with differentpolarization state in experiment successfully, which demonstrates the accuracy of thetheory and numerical analysis for CAA in practice.