Dipole Calculator

Created by Łucja Zaborowska, MD, PhD candidate
Reviewed by Bogna Szyk and Jack Bowater
Last updated: Dec 21, 2022

Our dipole calculator is a simple tool that allows you to compute the length of a simple antenna - it'll also provide you with the value of the wavelength and the adjustment factor [k].

In the text below, we will cover the basic rules of antenna construction, how to calculate dipole antenna length, and explain how to put our wire antenna calculator to work.

🙋 Head to our resonant frequency calculator to learn about the basics of LC circuits and the source of radiofrequency waves.

How to use the dipole calculator?

In order to use our antenna calculator, you'll need to know the frequency on which you want your antenna to operate.

Your result will consist of:

  • Your total antenna length (L);
  • Length of one arm of the antenna (l); and
  • Wavelength, as well as its portions: 1/2, 1/4 (it'll also allow you to use it as a 1/2 wave dipole calculator).

In the advanced mode:

You may enter the diameter of your conductor to obtain the adjustment factor [k]. You may need it for high frequencies and thick wires or if your antenna is made out of a tube.

Our wire gauge tool assesses the properties of a wire, such as its diameter and resistance 📎- feel free to try it!

🔎 The lengths used in our dipole calculator are inches, centimeters, and all other popular units. Feel free to play with the numbers however you like!

How is dipole antenna length calculated?

The antenna length formulas used in our dipole length calculator are as follows:

L = 468 / f,

l = L / 2,

where:

  • L - the length of the total dipole antenna in feet (ft);
  • l - the length of the arm of the dipole antenna in feet (ft); and
  • f - the desired frequency.

We also used the simple wavelength formula:

Wavelength = c / f,

where:

  • c - the speed of light: 299,792,458 m/s; and
  • f - frequency.

If you want to use the adjustment factor [k], you'll need the following version:

L = 0.5 × k × c / f,

where:

  • c means the speed of light; and

  • k is the adjustment factor, calculated with the following equation (simplified version):

    k= 0.9787 - [(11.86497 / (1 + (R/0.000449)1.7925)0.3)],

    where:

  • R = ½ wavelength / Diameter of a conductor.

🔎 If you don't feel confident switching between wavelength, frequency, or wavenumber units, our wavelength calculator will definitely help you with the task!

Dipole FM antenna length and construction

Dipole antennas are the easiest and probably the cheapest antennas to construct. They can give you a great insight into how antennas work and can be an excellent start for a beginner.

What will I need?

  • Some wire - usually made out of copper;

  • Insulators - should be placed on both ends of the wire;

  • A dipole centerpiece (an insulator can serve this purpose);

  • … with a feeder attached to it - usually a coax cable with an impedance of 50 Ω (remember to seal the endings!);

  • Fixings;

  • Two high-located, obstruction-free points to plant the antenna - the dipole's length is the most crucial feature to consider; and

  • Of course - our simple dipole calculator to assess the length of the device.

It is recommended to cut the wire a little bit longer than calculated and then trim it to the length that provides you with the best results.

FAQ

How can I calculate the length of an antena?

To calculate the length of an antenna, you may use the formula:

L = 468 / f,

l = L /2,

where:

  • L - Length of the dipole antenna;
  • l - Length of each arm of the dipole; and
  • f - Frequency.

Dividing 468 by the antenna frequency will give you the length of the antenna in feet.
Once you have the entire length, you can divide it by two and obtain the length of each arm of the dipole antenna.

What is a dipole antenna?

In the field of telecommunications, a dipole antenna is the most common type of antenna.
It comprises two conductors, hence the name dipole, which means two poles. The conductor is made in such a manner that it is half the length of the maximum wavelength the antenna can produce.
The two conductors, split in the middle, are separated by an insulator.

Can I calculate the wavelength of a dipole?

Yes, you can calculate the wavelength of a dipole. You may use the formula:

Wavelength = c /( f × 1,000,000),

where:

  • c - The speed of light equal to 299,792,458 m/s; and
  • f - The frequency of the antenna.

All you have to do is divide the speed of light by the product of frequency and 1,000,000. And as a result, you have the wavelength of the dipole antenna.

What is the dipole length with 3.7 MHz frequency?

If the frequency is 3.7 megahertz, the antenna length is 38.554 meters, and the dipole leg length is 19.277 meters.

The formulae to calculate the dipole antenna and leg length are:

L = 468 / f,

l = L /2,

where:

  • L - Length of the dipole antenna;
  • l - Length of each arm of the dipole; and
  • f - Frequency.
Łucja Zaborowska, MD, PhD candidate
Diagram for a dipole antenna calculator
Frequency
MHz
Results
Antenna length (L)
ft
Dipole leg length (l)
ft
Wavelength
ft
½ wavelength
ft
¼ wavelength
ft
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