Figure 4.

Crown and C-core coil performance as a function of target depth (dashed line: 4 cm, solid line: 6 cm) and coil size parametrized by angles α and γ (see Figure 1 for angle definitions). Left column: angle β of the crown coil is fixed at 40° while α is varied from 20°–90°. Varying angle β in the crown coil while holding α fixed at 90° results in similar trends (see Supplementary Figure S1). Right column: γ of the C-core coil is varied from 10°–180°. Evaluated metrics are: (a–b) maximum electric field strength in the cortex relative to neural activation threshold, max(∣E_{2 cm}∣)/E_th, (c–d) directly activated brain volume, V_A, and (e–f) energy delivered to the coil assuming E_th = 1 V cm⁻¹, W.