Research On Frequency Tunable Mesoband High Power Microwave Radiator And Technology

Mesoband high power microwave(HPM) takes wide frequency range of ultra-wideband HPM, high spectrum density of narrow band HPM, and high back door couplecoefficient into electric equipments, these make it to be a potential solution inapplications of vehical forced stopping, suppression of roadside bomb attack, and keyarea protection, however, these applications also request the mesoband HPM radiator tobe tunable and more compact. To improve gain-volume ratio of antenna and achievecenter-frequency tuning of mesoband pulse generator, the researches in this dissertationinclude:First, improvement of Taguchi optimization method for optimization design ofwideband patch antenna and coupler was investigated. To avoid disadvantage that thebased Taguchi method drops into local extremum points when solving problems withcomplicated fitness function, two procedures were introduced to the based searchingflow, they are randomly generation of new parameter levels and internal searching loop.Tests using typical multivariable functions indicated that, for most of the functions,optimal convergence rate rises from almost zero to more than80%after improvement.The improved Taguchi method has been successfully applied in optimization design ofhigh power wideband patch antenna and couplers in the dissertation.Second, a high power wideband patch antenna and array were investigated. Twolayer stacked patches and multilayer substrates structures were employed to widenbandwidth, a novel cone feed probe with low inductive reactance also was suggested.To improve power handling capacity of the antenna, sides of the two nylon substrateswere jointed to form a seal box for the first time, and filled SF6gas in the box.Measured bandwidth is as wide as64%after optimization designed by improvedTaguchi method, and gain-volume ratio is22.3dB. Compared with bipole andmonopole pulse, mesoband pulse is more appropriate for driving the antenna.Characters for radiating mesoband pulse of a2×2high power wideband patch antennaarray also was investigated.Third, a center-frequency tunable high power mesoband pulse generator wasinvestigated. We suggested a novel oscillator structure with a coupler and a moveable annular switch, then derived the relationships of oscillating, output response charactersand bandwidth against the coupler coefficient by frequency domain analysis. A lowfrequency band coupler and a high band one with quasi-constant coupler coefficientwere optimized. In FDTD simulation, mesoband pulses with center frequency rangedfrom200MHz to800MHz were output by moving position of the switch. Effect ofincompletely matched load on the oscillator's resonance character also was investigatedfor the first time.Last, high power experimental research of frequency tunable mesoband HPMradiator was carried out on a Tesla transformer plateform. Mesoband pulses with centerfrequency ranged from200MHz to800MHz are obtained in test of the pulse generator,the charging, oscillation, and output characters corresponded with results by theoryanalysis. Joint-test of the pulse generator and patch antenna verified the radiatingcharacters of the radiator, center frequency of radiated filed ranged from225MHz to350MHz, the maximum radiation factor was as high as183kV at333MHz, waves andspectrums after amplitude and phase compensation matched well with theoretical resultsby unmatched load effect analysis.Our researchs provided a novel high power wideband patch antenna with high gainvolume ratio for mesoband HPM radiator, derived the response functions of oscillating,output pulse and radiated field of the switched oscillator systematically, provided a wayto analysis switched oscillator efficiently, and achieved on-line frequency tuning ofswitched coaxial oscillator in experiment for the first time.