Methods for Noise Reduction in Far-Field Patterns Obtained From Cylindrical Near-Field Antenna Measurements

Abstract

Abstract-Two different methods to reduce the noise power in the far-field pattern of an antenna as measured in cylindrical nearfield (CNF) are proposed. Both methods are based on the same principle: the data recorded in the CNF measurement, assumed to be corrupted by white Gaussian and space-stationary noise, are transformed into a new domain where it is possible to filter out a portion of noise. Those filtered data are then used to calculate a far-field pattern with less noise power than that one obtained from the measured data without applying any filtering. Statistical analyses are carried out to deduce the expressions of the signal-tonoise ratio improvement achieved with each method. Although the idea of the two alternatives is the same, there are important differences between them. The first one applies a modal filtering, requires an oversampling and improves the far-field pattern in all directions. The second method employs a spatial filtering on the antenna plane, does not require oversampling and the far-field pattern is only improved in the forward hemisphere. Several examples are presented using both simulated and measured near-field data to verify the effectiveness of the methods.

Antenna surface measurement by near-field hemispherical scanning and related problems

“…表 表 表 7 不同信噪比平面波的仿真求解精度 拟 [28] , 本文直接对仿真得到的幅值数据添加噪声进行 我们进一步使用奇异值分解(Singular Value Decomposition, SVD)去噪算法对近场半球面幅值进行去 噪, 可进一步降低环境噪声对面形测量精度的影响 [29] .…”