20 m Dipole Length Calculator

This tool calculates the physical dimensions of a 20 meter (m) dipole antenna.

20 m refers to the wavelength of the transmitted and/or received signal.

Using the calculator below at 20 meters,

• the dipole length (L) is 31.2 feet
• the length of each element of the dipole (l) is half of that at 15.6 feet

Formula

The total length (L) of the dipole antenna is calculated as:

L = 468 / f

where f is the frequency in MHz.

f is calculated from the wavelength. For 20 m the frequency is 15 MHz.

The length of each arm of the dipole

l = L/2

Background

What is a Dipole Antenna?

The dipole antenna consists of two conductive elements. Hence the name dipole. The two elements are parallel to each other and separated by a gap. The current flows through both conductors and causes the antenna to radiate, creating an RF signal that is radiated outward from the antenna. The radiation pattern is maximum in the direction perpendicular to the dipole.

20 meter band

Radio communications utilizes different frequencies depending on the application. The 20 meter or 14 MHz band is used for amateur radio applications. It is a portion of the shortwave* radio spectrum, comprising frequencies stretching from 14.000 MHz to 14.350 MHz.

*The shortwave frequency range spans from 3 MHz to 30 MHz.

What is the 20 m band plan?

A band plan refers to a set of frequency allocations within a certain range, measured in GHz, MHz, kHz, designated for specific modes of communication. In the world of amateur radio, band plans are crucial for ensuring orderly and efficient use of frequencies.

Each amateur band has its own band plan to regulate the use of frequencies and avoid interference between users. The 20 meter band covers frequencies from 14 MHz to 14.35 MHz and is primarily used for long-distance communications. This band allows for various modes of communication such as CW (continuous wave) and digital modes. It’s a very popular amateur radio band – in fact the most popular for DXing.

Ham radio enthusiasts must have their own station and a valid amateur radio license to access these bands.Â Understanding and adhering to the band plan is essential to establishing contact with other amateur radio operators. By following the guidelines outlined in the band plan, operators can maximize their radio frequency usage and make the most out of their amateur radio experience.

20 Meters band plan

The table below shows the 20 m band plan