Antiguo aparato de 1902, idéntico a las líneas de Ernst Lecher originales de 1888. Las ondas de radio generadas por un oscilador Hertziano de chispa viajan desde lado derecho por los cables paralelos. Los cables están cortocircuitados en el extremo izquierdo, reflejando las ondas hacia atrás en los cables hacia el oscilador, creando una onda de voltaje estacionaria a lo largo de la línea. El voltaje se hace cero en los nodos, localizados en múltiplos de una media longitud de onda desde un extremo. Los nodos se detectan recorriendo los cables con un tubo de Geissler, un tubo de descarga luminiscente pequeño como una luz de neón. El voltaje alto en la línea produce un fulgor en el tubo. Cuando el tubo alcanza un nodo, el voltaje se reduce a cero y el tubo se apaga. La distancia medida entre dos nodos sucesivos es igual a la mitad de la longitud de onda λ/2 de la señal de radio. La línea  se muestra truncada en el dibujo; la longitud de la línea era de hecho de 6 metros (18 pies). Las ondas de radio producidas por el oscilador eran de la gama del UHF, con una longitud de onda de varios metros. El detalle muestra tipos de tubos de Geissler utilizados en las líneas de Lecher.
English: Drawing of an early demonstration Lecher line apparatus, from a 1902 catalog of scientific equipment. It is very similar to the first Lecher line built by Austrian physicist Ernst Lecher in 1888. A Lecher line is a pair of parallel wires or rods that were used to measure the wavelength of radio waves. In this example, the radio waves are generated by the Hertzian spark-gap oacillator (right) and sent down the Lecher line, the pair of parallel wires to the left. The Lecher line forms a length of balanced transmission line, along which the waves travel at the speed of light. At the left end of the line the two wires are connected together. This short-circuit termination reflects the waves back up the line toward the transmitter. The outgoing and reflected waves interfere with each other, creating a series of standing waves on the line. The voltage across the line goes to zero at nodes that occur at regular intervals of one-half wavelength (λ/2) from the end of the line. The distance between two nodes is measured and multiplied by two to get the wavelength λ. Since the waves travel at the speed of light, c, the frequency of the waves f can be calculated: f = c / λ {\displaystyle f=c/\lambda } To find the location of the nodes, a Geissler tube, similar to a small neon light, is suspended from hooks across the line and slid up and down the line. The high voltage waves cause it to glow. At the nodes the voltage goes to zero so the Geissler tube goes out. The inset (top left) shows the type of Geissler tubes that were used with Lecher lines. The Hertzian oscillator (right) generated radio waves in the UHF range, with wavelengths of a few meters, so a 6 meter Lecher line was used (the length is truncated in this drawing). The oscillator consists of an induction coil that generates a high voltage that jumps across a spark gap (center) many times per second. The two sides of the spark gap are coupled to the Lecher line through two parallel-plate capacitors (circles). The energy stored in the capacitors is discharged into the line during each spark, generating a brief oscillating radio wave (damped wave) that decays to zero. The symmetrical balanced circuit ensures that equal and opposite voltage waves are induced in each wire. Alterations to image: extended the length of the Lecher line, which was misleadingly shortened to several inches long in the original drawing to save space. Added inset showing closeup of Geissler tubes from nearby drawing in same source. Deutsch: Dieses Stehwellenmessgerät wurde 1888 vom Physiker Ernst Lecher entwickelt, um Wellenlängen und Frequenzen zu messen. Die Abbildung stammt aus einem Katalog für wissenschaftliche Laborausrüstung aus dem Jahr 1904 und ist für Wellenlängen um 1 m geeignet.