The inverse source technique is an accurate post processing and diagnostics method for antenna measurements [1-3]. Indeed, this technique has proven useful to suppress and filter disturbances in measurement scenarios such as presence of the feeding cable and mounting support [4-6]. Performing accurate measurements of on-chip antennas at millimeter wave frequencies is difficult in particular due to the nature of the electrical interface and the physical size of the antennas. The measurements are performed with electrically large probing and positioning equipment, causing interference with the measurement [7]. In this paper, we use the filtering properties of the inverse source technique to quantify and suppress the undesired scattering of the fields in the probing and support structure. To the knowledge of the authors, the filtering of such electrically large scattering objects has never been reported at millimeter wave frequencies. The effectiveness of the approach is demonstrated by measurements on a 60GHz patch antenna with integrated EBG structures.