Dipole Calculator

Our dipole calculator is a simple tool that allows you to compute the length of simple antennas, particularly the very efficient half-wave dipole antennas. It'll also provide you with your antenna's corresponding wavelength value and the option to use an adjustment factor [k] calculated using your dipole conductor's diameter.

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

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 and 1/4 the wavelength.

You can also calculate your total antenna length using the adjustment factor, k. You may need it for high frequencies and thick wires or if your antenna is made out of a tube. To calculate this, follow these steps:

1. Tick on the "Find adjusted antenna length" checkbox below the frequency variable.
2. Then, enter the diameter of your dipole conductor.
3. Our calculator will instantly give you the adjustment factor, the adjusted total antenna length, and the dipole leg length.

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

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

L = 468 / f

l = L / 2

where:

• L — Length of the total dipole antenna in feet (ft);
• l — Length of the arm of the dipole antenna in feet (ft); and
• f — Desired frequency in megahertz (MHz).

We also used the simple wavelength formula:

Wavelength = c / f

where:

• c — Speed of light: 299,792,458 m/s; and
• f — Frequency in hertz (Hz) to find the wavelength in meters (m).

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

L = 0.5 × k × c / f

where:

• k — 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

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.