This paper presents the design and implementation of a new swing arm gantry positioner having an 8-meter radius and a radial axis to support high frequency SNF measurements. Recent advances in the automotive industry have warranted a need for SNF systems with high mechanical positioning accuracy supporting measurements up to 40 GHz and beyond. While certainly these have been discussed previously in the literature, this paper consolidates the previous information and illustrates it with numerical examples to help the reader understand the best approach to use when repurposing a range.Īuthors: Vivek Sanandiya, Tim Schwartz, Eric KimĪbstract-Spherical near-field (SNF) systems using a swing arm gantry configuration have been the “go to” solution for automotive measurement systems. This paper also analyzes the performance of Chebyshev absorber for normal incidence and for oblique incidence along with the proper arrangement of the Chebyshev period. In this paper, numerical analyses of Chebyshev arrangements as well as dragon tail or tilted absorber are studied. In rectangular-shaped ranges for example, the lateral surfaces, side walls, ceiling and floor, are the critical surfaces to address in RF absorber arrangement. Thus, the performance of the range is mostly dependent on the RF absorber and the range antenna directivity. The inability to set the geometry precludes the range designer from using the range geometry to improve measurement performance. These existing ranges have fixed geometries (height, width and length) that were set when the range was originally constructed and often are designed for a different purpose. Brumley, "Improving the Performance of Anechoic Absorbers," in Proceedings of the 10th Annual meeting and Symposium of teh Antenna Measurement techniques Association (AMTA 1988), Atlanta, GA, Sep 12-16, 1988.Ībstract-Financial impacts often drive decisions to repurpose existing ranges instead of procuring new measurement facilities. The results validate the data and the suggestions presented in The numerical studies are done using time domain techniques as well as frequency domain techniques. In addition to the twisted pyramid, Brumley’s approach of inserting smaller pyramids in the valleys of a larger pyramidal arrangement to reduce the edges parallel to the incoming wave are also presented. Specifically, his recommendation for the so-called twisted pyramid configuration which he was unable to measure due to the lack of absorber for him to use in the test. In this paper the suggestions presented by Brumley are revisited. Brumley presents some potential ways of improving the RCS signature of the range thus reducing the background RCS of the site. The study was done empirically, doing measurements of the RF absorber, and looking at the RCS of different pyramids, with and without paint. Brumley studied the RCS of RF absorbers as a way to estimate the background RCS of anechoic ranges. These however, tend to focus on the reflectivity of the material not on the radar cross section (RCS) that it presents. Available on Novemat AMTA 2020 Virtual SymposiumĪbstract-There have been a number of numerical analyses of RF absorber.