Inductive wireless mobile charger circuit
The transferred power between two coils depends on the coupling inductance between them, which depends on several things, such as axial spacing, number of turns and radius of the coils, according to this formula:

$$ 
L_{12} = N_1.N_2.\frac{\mu_0}{2}.r_1.r_2.\int_0^{2\pi}\dfrac{cos\alpha}{\sqrt{b^2+r_1^2+r_2^2-2.r_1.r_2.cos\alpha}}d\alpha
$$

Being \$b\$ the axial spacing, \$r_i\$ the radius of the coils and \$N_i\$ the number of turns.
You can see how increasing the number of turns and radius will allow you to increase the axial distance to obtain the same coupling inductance, therefore the same transfered power.

See reference paper (page 5) Limitation of inductive power transfer for consumer applications