A system of three computer programs is described which process data from far-field amplitude antenna pattern measurements to give partial and total directivity mappings (where ‘partial directivity’ refers to one polarisation only). The measurement data is acquired by sampling the radiation distribution over a spherical region enclosing the test antenna, first in one polarisation and then in the orthogonal polarisation, so that two ‘spheres’ of information are contained in a measurement data set. A small binary/decimal conversion program processes the two parts of the data set individually, and a data package with a heading containing measurement specifications is then set up. The data package is processed by the main program which integrates to find the isotropic level and then the partial and total directivities, and prints out the values in tabular form. As well as the conversion and main programs, there is an optional program that prints out the contents of the data package in an easily viewable form. This is useful if the input data contains errors.