Adaptive Sampling in Spherical and Cylindrical Near-Field Antenna Measurements

An adaptive approach for optimized sampling in cylindrical and spherical near-field antenna measurements is described. The presented technique applies higher sampling density in rapidly varying near-field regions, and skips data points in the smoother regions. Abrupt changes in the near field are detected by comparing the extrapolated and the measured near-field values at coarser sampling points during the measurements. A decision function, based on the signal-to-noise ratio of the measured value, is used to determine the threshold difference between the extrapolated and the measured near-field values for skipping the sampling point. The reduced near-field data collected is processed using the fast irregular antenna field transformation algorithm (FIAFTA). FIAFTA is computationally efficient, and capable of handling data on irregular grids with full probe correction. Several test cases are then presented related to the applicability of the given approach. A significant reduction in the number of measurement points was observed, thereby reducing measurement time and the computational effort.

[1]  T.F. Eibert,et al.  Multilevel Plane Wave Based Near-Field Far-Field Transformation for Electrically Large Antennas in Free-Space or Above Material Halfspace , 2009, IEEE Transactions on Antennas and Propagation.

[2]  J. Hansen.  Spherical near-field antenna measurements , 1988 .

[3]  Ovidio Mario Bucci,et al.  Application of Nonredundant Sampling Representations of Electromagnetic Fields to NF-FF Transformation Techniques , 2012 .

[4]  E. Joy,et al.  Spatial sampling and filtering in near-field measurements , 1972 .

[5]  Flaminio Ferrara,et al.  An Efficient Near-field to Far-field Transformation Using the Planar Wide-mesh Scanning , 2007 .

[6]  Thomas F. Eibert,et al.  Adaptive Sampling in Multilevel Plane Wave Based Near-Field Far-Field Transformed Planar Near-Field Measurements , 2012 .

[7]  D. Paris,et al.  Probe compensated near-field measurements on a cylinder , 1973 .

[8]  Thomas F. Eibert,et al.  Electric dipole based synthetic data generation for probe-corrected near-field antenna measurements , 2011, Proceedings of the 5th European Conference on Antennas and Propagation (EUCAP).

[10]  Ovidio Mario Bucci,et al.  Use of sampling expansions in near-field-far-field transformation: the cylindrical case , 1988 .

[11]  R. Coifman,et al.  The fast multipole method for the wave equation: a pedestrian prescription , 1993, IEEE Antennas and Propagation Magazine.

[12]  F. Ferrara,et al.  An Effective NF-FF Transformation Technique With Planar Spiral Scanning Tailored For Quasi-Planar Antennas , 2008, IEEE Transactions on Antennas and Propagation.