Figure 25.

Layout of the reader and encoder of the absolute encoder system based on metallic patches, with motion direction detection capability. The total area of the encoder is 30 × 70 mm², with the following metallic patch dimensions: d₁ = 11.5 mm; d₂ = 15.9 mm, w = 3 mm, s = 1 mm and g = 1.9 mm. Reader dimensions are: l₁ = 26.6 mm; l₂ = 3.8 mm, l₃ = 10 mm, w₁ = 6.4 mm, w₂ = 1.9 mm, l_c = l_d = 10.5 mm; l_p = 14.5 mm, w_r = 2.9 mm. CSRR slots width is c = 0.5 mm, and ring splits are s_d = 0.4 mm, s_c = 1.6 mm and s_p = 6.2 mm. The encoders were implemented in the Rogers RO4003C substrate with thickness h = 0.81 mm, dielectric constant ε_r = 3.38, and loss factor tanδ = 0.0022. The reader substrate is identical but with a thickness of h = 0.2 mm. Reprinted with permission from [28]. Copyright 2020 IEEE.