Our paper on metagratings for perfect mode conversion in rectangular waveguides by postdoctoral fellow Dr. Vinay Kumar Killamsetty and Ariel Epstein was published in the Physical Review Applied, and was selected to be highlighted as Editors’ Suggestion. The paper extends the metagrating synthesis approach to enable complete power transfer from an incident TE10 mode into a reflected TE20 mode within a metallic waveguide. The analytical design is based on the analogy between beam interaction with a periodic surface and the effective periodicity formed by the metallic waveguide walls. The method points out favorable positions for a capacitively loaded wire, and the geometry of the load printed capacitor, to facilitate perfect mode conversion. The resultant fabrication-ready design (in the form of a small PCB card) is manufactured without any further optimization, and characterized using two different setups – S-parameter measurement with a VNA, and radiation pattern characteristics of the open-ended waveguide. Despite being fundamentally different, both measurements excellently agree with each other, pointing out that the fabricated prototype successfully couples more than 90% of the input power into the higher-order mode. These results form an original alternative to common mode converters, typically relying on structural deformation and extensive numerical optimizations.