The planar near-field measurement of a broad beam antenna using a synthetic subarray approach

Even though planar near-field measurements are best suited for narrow beam antenna testing, a broad beam antenna such as a standard gain horn, which is needed for a gain level reference, must often be measured in a planar near-field range. Typically, the accuracy of a broad beam antenna measurement is limited by the truncation error caused by the finite size of the scan plane and relatively large field levels at the edge resulting in an easily recognized "Gibb\´s phenomena" in the antenna patterns. The truncation error can be minimized by applying a window function to the raw near-field scan data; however, choosing the proper window function is not straightforward. In this paper, an insightful formulation of a near-field scan data window is presented. The physical interpretation of the formulation enables the selection of an appropriate window function for a given test antenna and range geometry.