A dipole antenna is one of the most common and effective antennas used in radio communication.
A dipole antenna length calculator helps you determine the right dimensions for your antenna based on the frequency you intend to use.
Calculator
Enter the frequency of operation and the tool will calculate antenna length in the metric systems.
Use the drop down menu to select the units: GHz/MHz/kHz for frequency and m/cm/mm for length.
Formula
The total length (L) of the dipole antenna in meters is calculated as:
L = 143 / f
where f is the frequency in MHz.
A dipole antenna is comprised of two arms of equal length
l = L/2
Example Calculations
Example 1: Dipole Antenna for 14 MHz
Let’s say you want to build a dipole antenna for a frequency of 14 MHz, commonly used in amateur radio. Use the calculator on this page to calculate the length to be 10.21 meters. That’s the total length. Each leg is 5.1 meters long
Example 2: Dipole Antenna for 7 MHz
Now, let’s calculate the length for a frequency of 7 MHz. Total dipole length in this case is 20.43 meters. The length of each leg is 10.21 meters.
What Is a Dipole Antenna?
A dipole antenna is a simple type of antenna that consists of two conductive elements (or “legs”), typically made from wire or metal rods. The total length of the dipole is related to the wavelength of the frequency it is designed to transmit or receive.
A half-wave dipole is the most common type of dipole, where the total length of the antenna is half the wavelength of the target frequency. Each leg of the dipole is one-quarter of the wavelength, and this antenna configuration is highly effective at transmitting and receiving signals within its resonant frequency range.
Why Use a Dipole Antenna Length Calculator?
The performance of a dipole antenna depends on its length being tuned to the wavelength of the desired frequency. If the antenna is too long or too short, it will not be resonant at the desired frequency, leading to poor signal transmission and reception. A dipole antenna length calculator simplifies the process by allowing you to quickly determine the correct length for each leg of the antenna based on the frequency you plan to use.
Tuning and Real-World Adjustments
While the formula provides a good starting point, real-world factors can affect the performance of your dipole antenna. For example:
- Surrounding objects, such as buildings or trees, can affect signal reception.
- Height above the ground can change the antenna’s resonance.
- Wire thickness and material can influence the final length.
To account for these factors, you may need to fine-tune your antenna after installation. This is typically done by slightly adjusting the length of each leg and using an SWR meter or antenna analyzer to check the signal performance.
