Re: 1/4 wave transmitter

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: FIFTYGUY@xxxxxxx 

In a message dated 5/7/06 3:39:01 PM Eastern Daylight Time, 
tesla@xxxxxxxxxx writes:

>>. . . myth . . . that the wire must be exactly 1/4  wavelength for
>>maximum efficiency.  Tesla made such an assertion during his early
>>research in the 1890's. . . .
>
>This sounds like an old oscillation of memory that needs to be
>refreshed. Can you provide a title and page number where Tesla's own
>words to this effect can be read?

    I recalled Tesla mentioning 1/4 wavelengths in his patents. A 
quick glance through the Jim Glenn compilation finds #645,576, 
"System of Transmission of Electrical Energy". This patent is yet 
another description of his basic scheme for using the upper 
atmosphere to transmit *power* at high frequency. The transmitting 
and receiving transformers are not described as "Tesla Coils", but 
they are both high voltage/high frequency transformers, and one would 
of course expect something like a CW Tesla Coil to be the transmitter 
he had in mind.
    From this patent:

    "The length of the thin-wire coil in each transformer should be 
approximately one-quarter of the wavelength of the electric 
disturbance in the circuit, this estimate being based on the velocity 
of the propagation of the disturbance through the coil itself and the 
circuit with which it is designed to be used. ... By such an 
adjustment or poportioning [sic] of the length of the wire in the 
secondary coil or coils the points of highest potential are made to 
coincide with the elevated terminals D D', and it should be 
understood that whatever length be given to the wires this condition 
should be complied with in order to obtain the best results."

    To me, this shows that:

1. Tesla used the 1/4 wavelength as a guideline only;
2. He understood that what was important was the "velocity of 
propagation" through each individual coil, which was dependent on the 
loading of the individual coil (among other things). There is no 
"universal" propagation velocity through all coils (i.e., the speed 
of light in a vacuum);
3. Even with this guideline, his design was to tune "to obtain the 
best results".


-Phil LaBudde