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STEP 03 / 06 · ABOUT 5 MIN

Divide the dipole

Two arms and a central feed point.

A centre-fed half-wave dipole has two equal arms. The calculator shows both overall length and the length of one arm. Using the overall length for each arm would make the antenna twice as long.

At 145 MHz and k = 0.95, the result is about 0.982 m overall and 0.491 m per arm. These starting dimensions are not a finished adjustment. Height above ground, nearby conductors and insulation alter real behaviour. Feed line and balancing belong in the installation plan.

Your turn.

Open the labelled dipole drawing. Change 145 to 435 MHz. Compare arm lengths and explain why they fall to one third.

Dipole drawing with a 145 MHz example →Read more: dipole →
UNDERSTAND & APPLY

Check your understanding

The calculator shows 0.982 m overall. How long is each equal arm?

Sources & further documentation

Your learning path— / 6
  1. Start with the purpose
  2. Turn frequency into length
  3. Divide the dipole
  4. Include the return path
  5. Separate SWR from loss
  6. Explain your design

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