# Antenna Length to Frequency Calculator

This tool uses the physical length of a dipole or monopole antenna to find the frequency of operation.

## Calculator

Enter:

• the length of the antenna and
• select the type of antenna
• 3/2 λ dipole
• 5/4 λ dipole
• λ dipole
• λ/2 dipole
• λ/4 monopole

The tool will provide the frequency of operation

## Example Calculation

To find the frequency of operation, first determine the type of antenna – i.e. is it a wire antenna (monopole) or a dipole. The most common type of dipole is a half wavelength.

Enter the physical length of the antenna (with the appropriate units) and select the type of antenna. The tool will provide the frequency it operates at.

• An wire antenna that is 10 m long will have an operating frequency of 7.5 MHz
• A half wave dipole antenna that is 10 meters operates at 14.26 MHz

## Background

### Dipole Antennas

A dipole consists of two identical conductive elements, such as metal wires or rods – each of length l in the picture below. This design calculator gives the dimensions based on frequency.

They are typically arranged end to end with a small gap at the center. This gap is where the antenna is connected to a transmission line, which feeds radio frequency (RF) energy to the antenna or receives energy from it. The dipole antenna operates by converting electrical energy into radio waves and vice versa.

The most common dipole length is λ/2 while the highest gain is associated with the 5λ/4 antenna. Wikipedia

### Monopole Antennas

Monopole antenna, sometimes called a Vertical is a very popular antenna type. It has a single radiating element erected vertically over the
ground.

The length of the antenna is λ/4, where λ is the wavelength. It uses a conductive surface to create a ground plane. Use this tool to calculate the length including that of the radials.