# Re: 1/4 wave transmitter

Original poster: FIFTYGUY@xxxxxxx In a message dated 5/7/06 3:39:01 PM Eastern Daylight Time, tesla@xxxxxxxxxx writes:
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>>. . . 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?

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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:

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"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."
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To me, this shows that:

1. Tesla used the 1/4 wavelength as a guideline only;
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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".
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-Phil LaBudde

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