Towards faithful radio transmission of very wide bandwidth signals

The necessary characteristics are derived for an antenna system which is to transmit efficiently and faithfully a very wide bandwidth (of an octave or more) signal. It is demonstrated that a suitable antenna for such a system may radiate isotropically in azimuth but be focused in all vertical planes. It is shown that a phase-corrected conical monopole is a convenient approximate realization of the antenna. Results are presented of an experimental investigation (inferring frequency responses from nanosecond time-domain-reflectometer techniques) of the driving-point and far-field responses of conical monopoles phase-corrected with cylindrically symmetrical lenses. Included is an experimental verification of previous theoretical predictions of the frequency dependence of the radiation which occurs when a transient is radiated from the base and the tip of a thin cylindrical monopole.