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New for March 2023. Load-pull contours are usually presented in two dimensions, similar to topological terrain maps. Did you know that Google Maps has topological capability, at least for mountains? You just need to click on the "layers" button on the lower eft and select "terrain". Below is a topo map of North America's southernmost ski area. It is hard to see on this image but there are actually numerical data. You can see it better if you generate it in your own browser, click here.
Back to the subject at hand. Sometimes it is better to look at a contour in a three-dimensional plot. DongPing sent us a nice 3D map of an active load-pull result. Active load pull allows you to get to unity reflection coefficient, which has always been the limitation of passive load-pull tuners. Read more about active load pull on this page.
Dongping explains the result in her own words:
I would like to contribute to Microwaves101 | Load Pull for Power Devices, a 3D active Load pull measurement results, which I obtained during my PhD work (from 2003 to 2008) at ESAT KUL (Department of Electrical Engineering, Katholieke Universiteit Leuven) and IMEC (Interuniversity Microelectronics Centre), under the supervision of Professor Dominique Schreurs and Professor Gustaaf Borghs. The GaN device was fabricated at IMEC, and the measurements were done at ESAT-TELEMIC.
Editor's note: please observe that the blue area of the contour is very close to the perimeter of the Smith Chart. Again, this is only possible with active load-pull equipment. Nicely done!