Impedance_Ohms 

           _____________________________
        ->()____________________________) <- d_cm
       |
    D_cm        Z_ohms sqrt(L/C)
       |   _____________________________
        ->()____________________________)
                      L_cm

  Z_ohms       =  276.0*log(2*D_cm/d_cm)
  C_pf/meter   =  12.06/log(2*D_cm/d_cm)
  L_uH/meter   =  0.920*log(2*D_cm/d_cm)