Far Field evaluation from undersampled Near Field measurements using numerically built basis functions

We show experimental results on evaluating the Far-Field (FF) pattern from measured Near-Field (NF) samples of a 8 GHz reflector antenna, where a radical undersampling on the data is applied. We reach an accuracy comparable to other standard methods. The key point is the use of additional information about the geometry of the antenna to numerically build a set of basis functions which are used to express the measured samples. Once approximated with these functions, the field can be easily evaluated on a finer grid of points or in the FF. The method can be easily applied with measurements performed on non-canonical grids