inductance calculation

1.two transmission lines ( one transmission line over ground plane)
============ t
h
============
<--- W ---->

Assume W>>h, h>>t, the partial inductance of the two-pair trace is

L_{trace_pair}\approx \frac{\mu_0 \mu_r h len}{W}

where u0= 4*pi nH/meter=32pH/mil (permeability of air), ur=relative permeability of the medium. len=transmission line length.
when len=W, L_trace=32pH*h (independent of the size of the square.)