Overcoming the typical limitations of the cylindrical nearfield to farfield transformation

The accurracy of the conventional cylindrical nearfield-farfield transformation technique suffers mainly from two facts: The non-ideal walls of the anechoic chamber cause multipath reflections and by sampling the field along the curved surface of a cylinder only, significant parts of the field, viz. those on top and bottom, are neglected. The paper deals with methods for overcoming these drawbacks. The multipath reflections are taken into account by mirror images, the incompleteness of the cylindrical envelope is avolded by applying the same conventional cylindrical technique sequentially to the test antenna in 2 orthogonal positions. The combination of these two methods leads to a significant improvement of the farfield results as derived from typical nearfield measurements.