Abstract :
The practically useful forms of series modulator are analysed, the results for the corresponding shunt modulators being shown to be readily derivable. The analysis of several of the circuits is carried out in a simpler manner than hitherto, and yet in all cases is sufficiently general to allow the variation of the mark/space ratio of the switching signal. It is shown that, in modulators with high impedance to unwanted products, a decrease of mark/space ratio from 1: 1 results in a decrease of conversion loss, whereas in those with correspondingly low impedance, an increase from 1: 1 results in a similar improvement. It is also shown that in the remaining cases a 1: 1 mark/space ratio gives optimum results. In every case the optimum values of terminations for the modulator for any mark/space ratio are found.
