Tesla's Hairpin is described in chapter 28 of Thomas Commerford Martin's book, "The Inventions, Researches and Writings of Nikola Tesla, with Special Reference to his Work in Polyphase Currents and High Potential Lighting". In the "Impedance Phenomena" section (pages 338 - 340). You probably already have this book in your personal library, but if not, you can download a copy in various formats from the Internet Archive site: http://archive.org/details/inventionsresear00martiala
Tesla's hairpin is actually a 3/4 turn rectangular inductor with two long sides and one short side at the far end. Tesla then connected a pair of HV capacitors, one to each end, of the inductor. The opposite ends of the HV capacitors were connected to a HV source and a spark gap - similar to a classic Tesla Coil "balanced" primary circuit. Each time the gap fired, the LC circuit formed by the inductor and caps would ring at their characteristic frequency. The RF voltage across any two points between the parallel wires would range from 0 (at the far end) to the peak supply voltage at the near end. You can easily duplicate Tesla's experiment by using a pair 1/2" copper pipes and fittings. Here's is an example of the inductive loop and spark gap built by one researcher:
You can use pulse-rated 30 - 40 kV ceramic doorknob caps in series with the lines to form the LC circuit.
BTW, you may find that Tesla's hairpin is sometimes described as being the same as Lecher lines. In reality, the two are actually quite different. Tesla's hairpin simply demonstrates the effects of inductive impedance at comparatively low RF frequencies (typically 100's of kHz - 10 MHz), and the effects do not require a stable frequency source or precise tuning. An example (from a "free energy" researcher) can be viewed here. Just short-circuit the far end of the line instead of leaving it open.
Lecher lines (see http://en.wikipedia.org/wiki/Lecher_lines) are actually balanced transmission lines that are driven at much higher frequencies (100's - 1000's of MHz), usually from CW sources. The far end of the lines can either be open or short circuited. Sometimes a sliding short circuit may be used to "tune" the lines to a given frequency or to measure an unknown frequency. When excited from a UHF/microwave source, standing waves form one (or more) nodes and antinodes at various points along the lines.
BTW, neither Tesla's hairpin OR Lecher lines require invoking "radiant energy", "longitudinal waves", or "scalar waves". The high frequency phenomena demonstrate simple physics of inductive reactance (Tesla's hairpin) or simple transmission line reflection and standing waves (Lecher lines).
Please let me know the results of your experiments.
I hope this helped and best wishes,
: G'day Bert,
: Recently I have been reading about a thing called the Tesla hairpin
: circuit, or the stout copper bars arrangement. I have never heard of this
: before in over twenty years of Tesla research and *fiddling*.
: Best I can find is something to do with radiant energy and, it would seem,
: a short form of wireless power transmission.
: Have you heard of this description, and if so can you direct me to simple
: plans and explanation of the concept.
: Beers and cheers,