电子定标法测试天线罩瞄准误差原理之分析

Analysis of Measurement of Radome Boresight Error by Electronic Calibration Method

论述了电子定标法测试天线罩瞄准误差的原理方法,并分析了该方法成立的理由。电子定标法的步骤依次为:收发天线机械轴对准→天线和差通道自检→收发天线电轴对准→电子定标→无罩测试→带罩测试→查表计算天线罩瞄准误差。电子定标原理和实测结果表明:测试过程中接收天线差电压与和电压之商,可分解为相对自检过程的共模分量和正交分量;定标过程共模分量保持不变,它决定天线的零深;正交分量随收发天线夹角变化,不受天线零深影响,其曲线为定标曲线;无罩和带罩定标曲线线性度极好,其斜率为天线差斜率;天线加装高性能天线罩后,差斜率变化微小;故可以使用无罩天线差斜率和带罩测试的和差通道电压,计算得出天线罩瞄准误差。差斜率近似引入的误差很小,电子定标法成立。

Measurement of radome boresight error （BSE） by electronic calibration method is described in this paper, and validity of the method is also analyzed. The steps of electronic calibration method are as follows ： adjust mechanical axes of transmitting antenna and receiving antenna to make them concentric perform self-check of antenna sum channel and difference channeladjust electronic bore-sight of transmitting antenna and receiving antenna to make them concentricperform electronic calibration--measure without radome and with radome successively--calculate radome bore-sight error by looking up table. From the theory of electronic calibration method and measurement datum, such results are concluded： in measuring process, channel voltage difference divided by channel voltage sum of receiving antenna can be decomposed into in-phase component and orthogonal component, which are in common with and orthogonal to that in self-checking process re- spectively. In-phase component keeps unchangeable while electronic calibration, and decides receiving antenna zero depth. Orthogonal component varies with the angle between transmitting and receiving antennas axes, which is called calibration curve, and has nothing to do with receiving antenna zero depth. Calibration curves with radome or without radome, both have very high linearity, and the slope of calibration curve is the difference pattern slope. Difference pattern slopes of antenna with high performance radome are close to that without radome, thus radome BSE can be calculated from difference pattern slope of antenna without radome, and voltages of sum and difference channels while measuring with radome. Approximation of difference pattern slope induces very low error while computing BSE, which proves the validity of electronic calibration meth- od.