Surface currents and charges on an electrically thick conducting tube in an E‐polarized, normally incident, plane‐wave field, 2, Measurements

The measurement of the surface densities of current and charge in both amplitude and phase over the entire surface of an electrically thick conducting tube (ka =1) when illuminated by an E‐polarized incident field is described. Use is made of a probe system consisting of a short monopole and two small mutually perpendicular shielded loops arranged to move axially as a unit along a groove in a thick‐walled aluminum tube which can be rotated through 360°. Graphs of the measured magnitude and phase of the axial and transverse components of the surface density of current and of the surface density of charge on the outside surface of the tube are displayed as functions of the axial and transverse variables. Problems of measurement and of the correlation of measured and theoretical values are discussed. It is concluded that with proper attention to detail accurate measurements can be made and the distributions of current and charge understood.