Verticals and radials

Posted on 21st Dec 2022

A vertical antenna is a popular choice for amateur radio operators because of its versatility and ability to transmit and receive signals in all directions. However, in order to work effectively, a vertical antenna must be installed properly and with the proper components. One of the most important components for a vertical antenna is a set of radials.

Radials are horizontal wires that run parallel to the ground and are attached to the base of the vertical antenna. They act as counterpoise, or ground plane, for the antenna and help to provide a stable and efficient electrical ground. This is important because it ensures that the antenna can transmit and receive signals effectively and reduces a small amount of unwanted interference.

One of the key reasons why radials are important is that they help to reduce the antenna's ground impedance. This is a measure of how much energy is lost as the signal travels from the antenna to the ground. By reducing the ground impedance, radials help to increase the efficiency of the antenna and ensure that it can transmit and receive signals effectively.;

Another reason why radials are important is that they help to reduce the amount of unwanted noise that can interfere with the signals being transmitted and received. This is because radials help to reduce the electrical noise that is generated by the antenna and its surrounding environment.

Additionally, the number of radials used also has an impact on the performance of the vertical antenna. The general rule is to use at least four radials, however, the more radials used, the better the performance of the antenna. Ideally, the length of the radials should be equal to or greater than one quarter of the wavelength of the frequency being used. This helps to ensure that the radials are providing a stable and efficient electrical ground for the antenna.

In some cases, the use of elevated radials can also improve the performance of a vertical antenna. Elevated radials are radials that are installed above the ground, rather than being attached directly to or laying on the ground. They help to improve the performance of the antenna by increasing its height above the ground and reducing the amount of interference from the ground.

It is also important to note that the material used for the radials can also have an impact on their performance. Copper is the most commonly used material for radials, as it is an excellent conductor and provides a stable and efficient electrical ground. However, other materials such as aluminum and steel can also be used, although they may not provide the same level of performance as copper.

The length of the radials is one of the most important factors to consider when installing a set of radials for a vertical antenna. The length of the radials affects the performance of the antenna by influencing its electrical ground and impedance.

In general, it is recommended to use radials that are equal to or greater than one quarter of the wavelength of the frequency being used. This helps to ensure that the radials provide a stable and efficient electrical ground for the antenna, and that the signals transmitted and received are strong and reliable.

For example, if the frequency being used is 14.2 MHz, the wavelength is approximately 21 meters. In this case, the length of the radials should be at least 5.25 meters although preferably 10.5 meters.

It is important to note that longer radials can provide better performance for the antenna. To a degree you can think of these radials laid out as a mirror to reflect the power back to the vertical radiator. However, the length of the radials should also be practical for the installation, as longer radials can be more difficult to handle and install.

For elevated radials, the height also affects their performance. It is recommended to install the radials at a height of at least 2 meters above the ground, as this helps to reduce interference from the ground and increase the performance of the antenna.

In conclusion, the length of the radials is a critical factor to consider when installing a set of radials for a vertical antenna. By using radials that are equal to or greater than one quarter of the wavelength of the frequency being used, and installing any elevated radials at a height of at least 2 meters, amateur radio operators can ensure that their radials provide a stable and efficient electrical ground for the antenna, and that the signals transmitted and received are strong and reliable.

_{Curtis Turner - KB3CMT}