Geometric spreading in a moving-receiver diffraction measurement ($I(d)\propto \mathcal{T}[v(d)]/(d_1+d{)}^2$)

A diffraction-loss ratio is normalized to the unobstructed intensity at the same receiver position. With a point source that unobstructed intensity changes as inverse source–receiver distance squared. Moving the receiver can therefore decrease the transmission ratio while increasing its absolute received intensity. The two curves require separate normalization; a Cornu-chord plot alone omits geometric spreading.