Efficient calculation of surface impedance for rectangular conductors

The Letter presents a new expression for the frequency-dependent surface impedance of a rectangular bar that is easily used, and is numerically efficient. By dividing the metal bar into rectangular and square sections, skin depth-induced current crowding to the surfaces and corners can be accurately modelled. Comparison with measured data shows excellent agreement over a wide frequency range, covering the transition from DC-like behaviour to skin-depth limited behaviour.