The fact that radio jets, which are often one-sided, are nevertheless associated with extended lobes of nearly equal luminosity indicates when analyzed in detail (1) that the energy supply by the nuclear engine to the lobes is strongly time-dependent. Time dependent ejection from the nucleus of a parent galaxy produces low density channels which are ploughed in the background medium by the passage of intermittently ejected radio emitting plasmons (2), (3), (4) and (5). An analysis of the dynamics of radio emitting plasmons in such channels leads to unique morphological features consistent with observations of both narrow jets (resulting from splashback or reflections from the channel ends) and conical lobes (resulting from slower hydrodynamic deceleration).