AZO透明导电膜电磁散射光电参数影响试验

采用常温镀膜技术在浮法玻璃表面沉积了不同方块电阻的氧化锌铝(Al-doped zinc oxide,AZO)透明导电膜,建立了透明导电膜的雷达散射截面(radar cross section,RCS)测试和研究方法;提出了基于雷达散射截面均值的相对反射率概念,结合方块电阻和可见光透过率综合分析了氧化锌铝透明导电膜的电磁散射特性.在微波暗室对不同方块电阻的氧化锌铝透明导电膜进行了测试,得到了10 GHz和15 GHz入射频率,水平(horizontal horizontal,HH)、垂直(vertical vertical,VV)极化的雷达散射截面曲线;从飞行器座舱隐身角度出发,研究了前向20°和60°角域雷达散射截面曲线分布特点,并分析了雷达散射截面均值影响特性;基于氧化锌铝透明导电膜雷达散射截面测试结果,研究了方块电阻对雷达散射截面相对反射率和可见光透过率的影响规律.研究表明,方块电阻较低时雷达散射截面曲线分布特性与对应金属相似,方块电阻增大时,前向两个角域内的RCS均值减小,隐身性能减弱,雷达散射截面相对反射率降低而可见光透过率增加,相对反射率降低速率大小与方块电阻相关,合适的方块电阻可同时满足隐身及采光需求.暗室测试结果表明,在满足座舱可见光透过率前提下,氧化锌铝透明导电膜方块电阻为18~45 Ω时,具有外形隐身作用,方块电阻18 Ω为最优,对应RCS相对反射率Re_m2和Re_dB分别为84%和0.73 dB. 

Influence of photoelectric parameters for AZO transparent conductive films on electromagnetic scattering characteristics

Al-doped zinc oxide (AZO) transparent conductive films with different sheet resistances were deposited on the surface of float glass by a room temperature coating technique. The procedure for radar cross section (RCS) measurements for AZO transparent conductive films was established, and the definition of the relative reflectivity based on the RCS mean value was proposed. The electromagnetic scattering characteristics for the AZO transparent conductive films were analyzed by way of the sheet resistance and visible light transmittance. The AZO films with different sheet resistances were tested in the microwave darkroom and RCS curves for the films were obtained with incident frequencies of 10 GHz and 15 GHz and in the HH and VV polarizations modes. The characteristics of the RCS curve distribution in angular domains of 20° and 60° in the nose direction and the characteristics of RCS mean values were analyzed to study the stealth performance for aircraft cockpit glasses. The influence of the sheet resistance on RCS relative reflectivity and visible light transmittance was studied based on RCS test results from the AZO transparent conductive films. When the sheet resistance was small, the distribution of the RCS curves was similar to that of their corresponding metal. When the sheet resistance increased, the RCS mean values in the angular domains of 20° and 60° in the nose direction decreased and the stealth performance was reduced. In addition, the RCS relative reflectivity decreased and the visible light transmittance increased. The rate of the decrease in the relative reflectivity was related to the sheet resistance. It was determined that an appropriate sheet resistance can meet the needs of stealth and lighting simultaneously. The results achieved from darkroom test also proved that upon meeting the requirement of visible light transmittance for aircraft cockpit glasses, the AZO transparent conductive film could provide shaped stealth performance when the value of sheet resistance was between 18 Ω to 45 Ω. When the sheet resistance was 18 Ω, the best performance of AZO appears with a relative reflectivity, Re_m2 of 84% and Re_dB of 0.73 dB.