Effects of cable and peripheral placement on radiated emissions

A number of antenna geometries are examined for radiation resistance and input reactance. More importantly, the effects of apparently small changes are evaluated to determine the frequency dependence of the equipment under test antennas. The models given are evaluated for frequencies up to 100 MHz; this the region where most cable-related effects are observed. The geometries considered are normalized to 1-m cables. Small changes are then made to the layout, followed by a reevaluation of the antenna effects. No attempt is made to provide information as to the directivity of these geometries. The models presented are based on single open-circuit (monopole) and closed circuit (loop) antennas. It is shown how some very-well-shielded and properly bonded cables must be included into the antenna model.<>