The elements of wave propagation using the impedance concept

The elements of propagation of radio waves are developed from the ordinary theory of transmission lines, familiar to electrical engineers, without any explicit reference to Maxwell´s equations. Phenomena such as the Brewster angle, the critical angle, propagation in hollow metal pipes, reflection and transmission by wire netting, etc., are all counterparts of well-known phenomena in the theory of transmission lines. The most powerful instrument for integrating all these phenomena into a single picture is the concept of field impedance. Just as potential difference (measured in volts) divided by current (measured in amperes) leads to the concept of circuit impedance, so electric field (measured in volts/metre) divided by magnetic field (measured in amperes/metre) leads to the concept of field impedance. Widespread use of the concept of field impedance was overdue before the war but has to some extent come into its own during the war.