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Re: 1/4 wave transmitter

Original poster: Mddeming@xxxxxxx In a message dated 5/6/06 10:04:48 P.M. Eastern Daylight Time, tesla@xxxxxxxxxx writes:
Original poster: "Langer Giv'r" <transworldsnowboarding19@xxxxxxxxxxx>

Hey everyone, I have been wondering for a while, where does the 1/4
wave setup get its name from?  (ex how does it transmit in a 1/4 wave)?

Thanks a lot

Hi Langer,

Without breakout, a Tesla coil normally will have the minimum voltage at or near the bottom and maximum at or near the top, while current is maximum at the bottom and minimum at the top. This is the distribution pattern of a 1/4 wave at the operating frequency. Also, to a crude approximation, a TC of "average proportions" will frequently have a wire length "in the neighborhood" of 1/4 it's unloaded operating frequency. This has given rise to a lot of myths over the last hundred years or so 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.It has since been repeatedly shown that this is not valid, but those who would burden Tesla with infallibility as well as genius keep propagating the myth.
    A moment's reflection will show that this is unreasonable:
1) Propagation along a coil is not the same as propagation along a straight wire. 2) Adding a topload drops the operating frequency ~50% and alters the current distribution. 3) Streamer formation also drops the operating frequency so that it varies with each spark.
Obviously, if an exact match were necessary, a TC could never operate properly.
Similarly, a double-ended coil, fed from the middle shows voltage and current distribution patterns similar to a 1/2 wave antenna,

Matt D.