超低旁瓣天线平面近场测量中随机误差对远场方向图的影响

Effect of random errors of planar near-field measurements with ultra-low sidelobe antennas on antenna far-field pattern

为了增强现代舰用天线系统的抗干扰能力,必须提高天线旁瓣的测量精度.基于此给出了用平面近场技术测量超低旁瓣天线时,旁瓣测量总误差与待测天线参数、近场幅相随机误差的数学模型:在相同的测量条件下,天线旁瓣越低,旁瓣测量误差越大;旁瓣测量总误差随着近场测量幅相误差的增大而增大;近场分布的口径效率与旁瓣电平的误差方差成反比.建立了近场幅相随机误差所引起的误差谱的表达式.对随机误差对远场方向图的影响进行了计算机仿真验证:结果表明,幅相误差主要影响远场方向图的旁瓣;该验证方法首次采用阵元数较少的线阵,仿真效果接近采用多阵元平面阵的情况.

The expressions of sidelobe measurement errors versus the relative parameters of antenna under test (AUT) and near-field amplitude and phase random errors are presented by using a planar near-field technique to measure ultra-low sidelobe antennas. It is concluded that: under the same conditions, sidelobe measurement errors will be larger if the antenna sidelobe level is lower. The caliber efficiency of near-field distribution is in inverse proportion to the error variance of the sidelobe level. This shows that the amplitude and phase errors mainly affect a far-field pattern's sidelobe level. The expression of error spectra caused by near-field amplitude and phase random errors is built and the related computer simulations are presented.