The "final design" is the chamfered bend with additional vias, a design with two 45° bends was not studied in this paper. Page 2, second paragraph of section A

The "final design" is the chamfered bend with additional vias, a design with two 45° bends was not studied in this paper. Page 2, second paragraph of section A : > The final design that includes both the chamfered bend and the vias