5-3
Figure 5-1.—Antenna current increase with amplitude modulation.
The use of this formula is based on the assumption that the modulating voltage is a pure sine wave.
Normal broadcasting, however, is characterized by complex envelope patterns, as illustrated in figure 5-2.
In this light, the previous formula is not so clear. Consequently, the preceding formula should be viewed
more correctly as the PERCENTAGE OF POSITIVE PEAK MODULATION. When the minimum
voltage (E
min) rather than the peak voltage (Emax) is used to compute percentage of modulation, the
computed percentage (shown below) is the PERCENTAGE OF NEGATIVE PEAK MODULATION:
