As Fig. 8 but for W1 (top), W3/W4/W5 (middle) and the G173 complex (bottom) published in Paper II showing depolarization along the periphery of H ii complexes. Depolarization of the indicated sector (position angles between  − 16° and  − 97°) in the outer periphery of W1 is modeled in Sect. 3.4. Total intensity contours of the W1, W3/W4/W5 and G173 complex start at 6.0, 6.0, and 3.0 mK T_B, respectively, and increase in steps of 2ⁿ × 3.6 mK T_B, with n = 0,1,2,...