Link Budgeting 101: How to Get Started

Selecting the right antenna is only part of the process when setting up a radio communications system. We can’t stress this enough. There are critical preliminary steps that you need to take in order to ensure a successful deployment.

For example, in a recent post we discussed the importance of conducting an RF propagation analysis, which involves collecting a variety of information to help predict how radio waves will travel from one point to another over a geographical area.

“Our approach is focused on setting appropriate expectations for our clients, so they can make more informed decisions about their network,” explained Afterimage GIS CEO Paul Shanayda, whose company provides geospatial information consulting services. “For a given area of interest, we look to our database for terrain, clutter, antenna patterns, and other link budget inputs.”

Shanayda touched on another key point here that you will want to consider, which is link budgeting.

What link budgeting?

A link budget can be defined as a measurement of the total transmitted power in a radio system, including all gains and losses. Calculating the link budget will help you determine your overall signal strength. This process is crucial when setting up high frequency radio links, as well as satellite and mobile transmissions systems.

Calculating a link budget is important for a few reasons. For instance, it will tell you whether you have enough power and gain in a transmission, enabling you to take action if the levels are too high or too low. If you don’t have enough power and gain, you will have a weak signal. If you have too much power and gain, you may be able to switch to a less powerful antenna or reduce your total transmission power, which can save money.

How to calculate a link budget

You can use software to help with link budgeting, and there are a variety of free tools available online. However, it’s important to have a basic understanding of how the process works. You don’t actually need software to calculate a link budget.

To perform an accurate calculation, you’ll need to consider all of the gain and loss involved in a particular link. Your total calculation should include the following:

• Transmitted power
• Receiver antenna gain
• Transmitter antenna gain
• Transmission feeder loss
• Receiver feeder loss
• Path and propagation loss

 Based on these factors, a basic link budget equation may read as follows:

Signal strength= transmitted power + Gains – losses.

One thing to keep in mind is that antennas have varying levels of radiation and gain. It’s very important to take these varying gains, and their direction, into consideration when calculating a link budget. Otherwise, your reading could be skewed.

For more information about this topic, or to find how KP Performance can help ensure a smooth deployment process, contact us today.