THE FIELDS DUE TO A SMALL LOADED LOOP IN FREE-SPACE

A theoretical analysis of a resistively loaded, electrically small loo p is presented which shows the variations of the transverse-wave imped ance close to the loop as the resistive loading is altered. The theore tical results are compared with those obtained from a numerical simula tion using Numerical Electromagnetics Code (NEC). Depending upon the l oading, the loop exhibits electric (high wave impedance) or magnetic ( low wave impedance) dipole properties, or intermediate wave impedances . These changes in wave impedance are closely related to variations in the far-field radiation pattern, and simulations are used to demonstr ate this. Measured results are used to demonstrate that the variations predicted in wave impedance actually occur in practice. These results have bearing on the interpretation of emission measurements and on th e design of circuits to minimize interference to other neighboring cir cuits.