WAVE SHAPES USED IN HARMONIC PRODUCERS 339 



The frequency spectrum of this wave is shown in Fig. 6. The original 

 standard frequency mco/lir is present and on either side above and below 

 co/27r cycles apart are additional components. The rate at which the am- 

 plitude of these frequencies dies out depends on the modulating pulse width 

 and is equal to half the amplitude of the corresponding harmonic in Fig. 2. 



If the standard frequency is not a pure wave but contains harmonics 

 each of these harmonics will be modulated by the rectangular pulses, that is 

 the function (16). The result will be a series of frequency spectra similar 

 to the one in Fig. 6, each centered at one of the harmonics of the standard 

 frequency. By proper choice of the frequency of the modulating wave 

 these spectra may be made to overlap giving a continuous series of harmonic 

 of the modulating frequency with much larger amplitudes than can be 

 obtained from a straightforward harmonic generator. As an example, a 

 one-megacycle wave heavily modulated with 100 kc was found to give strong 

 100 kc harmonics up to well over 35 mc. 



Acknowledgment 



These analyses were originally made in connection with a research pro- 

 gram at the Polytechnic Institute of Brooklyn. The author wishes to thank 

 Professor E. Weber of this Institute for verifying the derivation of these 

 equations. 



