J-pole antenna
Zepp' like antenna
The J-pole antenna, more properly known as the J antenna, is a vertical omnidirectional transmitting antenna used in the shortwave frequency bands. It was invented by Hans Beggerow in 1909 for use in Zeppelin airships. Trailed behind the airship, it consisted of a single one half wavelength long wire radiator, in series with a quarter-wave parallel transmission line tuning stub that matches the antenna impedance to the feedline. By 1936 this antenna began to be used for land-based transmitters with the radiating element and the matching section mounted vertically, giving it the shape of the letter "J", and by 1943 it was named the J antenna. When the radiating half-wave section is mounted horizontally, at right-angles to the quarter-wave matching stub, the variation is usually called a Zepp antenna.
How it works
The J-pole antenna is an end-fed omnidirectional half-wave antenna that is matched to the feedline by a shorted quarter-wave parallel transmission line stub. For a transmitting antenna to operate efficiently, absorbing all the power provided by its feedline, the antenna must be impedance matched to the line; it must have a resistance equal to the feedline's characteristic impedance. A half-wave antenna fed at one end has a current node at its feedpoint, giving it a very high input impedance of around 1 000–4 000 ohms. This is much higher than the characteristic impedance of transmission lines, so it requires an impedance matching circuit between the antenna and the feedline.
A shorted quarter-wave stub, a transmission line one quarter of the wavelength long with its conductors shorted together at one end, has a similar high impedance node at its open end, making a good match to the antenna.
“J-pole antenna” enters the record as zepp' like antenna. Crown Archives preserves that source wording while asking what J-pole, antenna and Zepp' can confirm, complicate or overturn.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Nov 9, 2025. The linked authority identifier is Q6103845. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1909, 1936 and 1943.
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This entry incorporates text from “J-pole antenna” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.