12.4.3 Current Distribution On Dipoles And Monopoles
Figure 12.15 illustrates the current distribution for a half-wave dipole and a quarter-wave monopole. The current is maximum at the center (or base, for the monopole) and zero at the ends. Since radiated power is proportional to the square of the current, regions of maximum current contribute most strongly to radiation. As antenna length is reduced (Figure 12.16), the current magnitude decreases. Even with tuning to restore resonance, shortened antennas cannot achieve the same radiation efficiency as full-length elements because the overall current distribution is diminished.
