 
Summary: Planar NearField Antenna Measurements Using
Nonideal Measurement Locations¤
R. C. Wittmann, B. K. Alpert, and M. H. Francis
National Institute of Standards and Technology
325 Broadway, Boulder, CO 803033328
Abstract The standard planar neareld to fareld
transformation method requires data points on a plane
rectangular lattice. In this paper we introduce a trans
formation algorithm in which measurements are neither
required to lie on a regular grid nor are strictly conned
to a plane. Computational complexity is O(N log N),
where N is number of data points. (Actual calculation
times depend on the numerical precision specied and on
the condition number of the problem.) This algorithm
allows e˘cient processing of neareld data with known
probe position errors. Also, the algorithm is applicable
for other measurement approaches, such as planepolar
scanning, where data are collected on a nonrectangular
grid.
Keywords: neareld antenna measurements; planar
