Semiconductor dipole: possible radiating element for microwave/millimetre-wave monolithic integrated circuits (MIMICs)

A wideband, semiconductor-compatible dipole, derived from the conventional metallic half-wavelength dipole is described. This dipole is resistively loaded along its length, producing a travelling wave current distribution that is insensitive to frequency variations. The resistive loading, however, produces a reduction in efficiency but an increase in bandwidth. Graphs are presented which relate the resistive loading, with efficiency and bandwidth for a given length to diameter ratio of the dipole. These graphs could be useful as design curves in th tradeoff between bandwidth and efficiency. The current distributions along the length of the dipole under various resistive loading conditions are also plotted, as well as the radiation patterns due to these current distributions. The resistive loading for a conventional dipole can be achieved by varying the thickness of the resistive material coating along the length of the dipole. For a semiconductor, however, the resistivity can be varied by changing the doping concentration (N_D) of the impurities. Hence, a wideband resistively loaded dipole can now be realised on a semiconductor substrate.