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J-pole antenna calculator

About

This calculator works out the dimensions of a J-pole antenna (the J antenna). The J-pole is a popular type of vertical antenna for the VHF and UHF bands.

Стандартні частотиJ-pole Antenna
Робоча частотаМГц
Діаметр дротумм
Одиниці вимірювання
Результат
Довжина хвилі (λ)см
Розмір Aсм
Розмір Bсм
Відстань Cсм
Розмір Dсм
Коефіцієнт укорочення-
Notes
  • Standard frequencies: pick one from the list of common frequencies or enter your own by hand.
  • Units: results can be shown in millimetres, centimetres or metres.
  • Dimension A — the length of the upper radiating element (3/4 λ).
  • Dimension B — the length of the lower element (1/4 λ).
  • Distance C — the distance from the feed point to the lower end.
  • Dimension D — an extra dimension used for tuning.
  • The velocity factor is calculated automatically from the frequency and the wire diameter.
  • The wire diameter affects the velocity factor and the overall dimensions of the antenna.
  • For best results, use wire of 2–6 mm diameter.
  • The antenna can be built from wire, tubing or metal strip.
Calculator by UR3PKI

The most recent versions are available on the author's site: CYBERDEV.SPACE - J-pole