A. In electronics, a Lecher line or Lecher wires is a pair of parallel wires or rods that were used to measure the wavelength of radio waves. The Lecher wire experiment found in undergraduate laboratories is usually limited to the observation of the voltage distribution for open and short circuit. An improved Lecher wire experiment. To cite this article: M B Allenson et al Phys. Educ. 8 View the article online for updates and enhancements.

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File:Lecher wires and oscillator png – Wikimedia Commons

Another way would have been to use e. Something else is still up….

You are commenting using your WordPress. The uniform spacing of the wires makes them a transmission lineconducting radio waves at a constant speed very close to the speed of light. To really make this article shine, it would have been nice to go back and verify the measurements with some known standard. This page was last edited on 22 Novemberat You only do that if you want correct results.

With care, Lecher lines can measure frequency to an accuracy of 0. See the red line in this photo.

Lecher line – Wikipedia

You guys should do a retrotachular on ECGs. Wlre the other end the rods are connected together with a conductive bar between them. You might have to remove paint from part of it the backside? The high voltage of early transmitters excited a glow discharge in the gas. When the screwdriver is still less than half a meter from the oscillator end, and at the node for the first half-wavelength, lecheer voltage across the diode is above 0.

By using lecheer site, lecger agree to the Terms of Use and Privacy Policy. Graph of the data. Views Read Edit View history. The other method used to find the nodes is to slide the terminating shorting bar up and down the line, and measure the current flowing into the line with an RF ammeter in the feeder line.


Notify me of new comments via email. Or if you rather use technology from 2 centuries ago, use that I suppose. Why does this so drastically differ from the values in the datasheet? Looking for more high frequency measuring projects here on Hackaday? Enhanced version and more background: There was a 90 MHz signal of unknown origin that dominated and the induced signal from the oscillator was lower amplitude so it rode on the 90 MHz signal.

There is wooden base under wires.

This was an important confirmation of James Clerk Maxwell ‘s theory that light was an electromagnetic wave like radio waves. They are used because at UHF frequencies the value of inductors lecber capacitors needed for ‘ lumped component ‘ tuned circuits becomes extremely low, making them difficult to fabricate and sensitive to parasitic capacitance and inductance. Because the speed of light in a transmission line is not the same as in vacuum. Also in my setup the other end of the wirr is open, the wires are not connected together there.

A major attraction of Lecher lines was they were a way to measure frequency without complicated electronics, and could be improvised from simple materials found in a typical shop. The waves reflected from the short-circuited end interfere with the outgoing waves, creating a sinusoidal standing wave ledher voltage and current on the line. So the distance my screwdriver was off by levher 0.

Check this out it probably has a few other neat methods in it too: More fun discovering Lecher Lines though. Part of that loop is a 6.


Two methods are employed to find the nodes. From Wikimedia Commons, the free media repository. When the screwdriver is between nodes, the voltage is less than 0. Thanks for suggesting that. Therefore the magazine’s copyright was not renewed and it is in the public domain. The length of the wires depends on the wavelength involved; lines used for measurement are generally several wavelengths long.

File:Lecher wires and oscillator 1932.png

How do you test the oscillator circuit you just made that runs between MHz and Wre if all you have is a MHz oscilloscope, a few multimeters and a DC power supply? The voltage goes to zero at nodes located at multiples of half a wavelength from the end, with maxima called antinodes located midway between the nodes. Austrian physicist Ernst Lecherimproving on techniques used by Oliver Lodge [3] and Heinrich Hertz[4] developed this method of measuring wavelength around This work is in the public domain because it was published in the United States between and and although there may or may not have been a copyright notice, the copyright was not renewed.

The shorting bar is slid down the line and the position of two successive current minima is noted, the distance between them is half a wavelength. Fill in your details below or click an icon to log in: The separation between the Lecher bars does not affect the position of the standing waves on the line, but it does determine the characteristic impedance lecer, which can be important for matching the line to the source of the radio frequency energy for efficient power transfer.