Unlocking the Power of Antenna Gain: How to Optimize Range and Coverage for Your Gateway Antennas

When it comes to maximizing the performance of your IoT network, understanding antenna gain is very important. Because whether you’re deploying a new gateway antenna or optimizing your existing setup, the right antenna can make all the difference.

With over 20 years of experience in LoRaWAN solutions, TEKTELIC team have put together a clear guide on antenna gain, its impact on range and coverage, and how to choose the best external antenna for your needs.

What is Antenna Gain?

Antenna gain is an important factor that affects how well an antenna sends and receives signals. In simple terms, gain tells us how well an antenna focuses its signal in one direction compared to a perfect antenna that spreads signals evenly in all directions.

A perfect antenna would spread signals equally in every direction, like a ball. But real antennas don’t work this way. They focus signals more strongly in some directions, which means you’ll get better range in those directions but less coverage overall. This balance is important when choosing the right antenna for your IoT network.

Omnidirectional vs. Directional Antennas

Understanding the difference between omnidirectional and directional antennas is essential for optimizing your network:

• Omnidirectional Antennas: These antennas typically have a gain between 0 dB and 3 dB. They radiate signals fairly evenly in all directions, resembling a doughnut shape rather than a perfect sphere. Omnidirectional antennas are ideal for scenarios where broad coverage is needed, such as in a large warehouse or open area.
• Directional Antennas: These antennas have higher gain and focus the signal in a specific direction. This design can significantly extend the range in that direction but at the expense of coverage in other directions. If you need to target a specific area, such as a remote corner of a facility, a directional antenna can provide the necessary range.

How Antenna Gain Affects Your Network

Antenna gain is measured in decibels (dB). The higher the gain, the more directional the antenna becomes. For instance, a 3 dB increase in gain doubles the signal power, while a 6 dB increase doubles the range. However, it’s important to remember that increasing gain doesn’t amplify the signal itself; it focuses the existing energy into a narrower beam.

Think of it like a water balloon: the volume of water represents the total signal power. No matter how you reshape the balloon, the volume remains the same. By adjusting antenna gain, you’re changing the shape of the balloon—making it longer and narrower, but not increasing the total volume of water.

Another analogy would be comparing a light bulb to a torch, representing an omnidirectional antenna and a directional antenna, respectively.

Although signal reception becomes narrower with increased antenna gain, a common technique is to use a diversity receiver. This allows multiple antennas to work together, constantly checking the signal strength of each antenna and selecting the one with the strongest signal. This approach can achieve both longer range and wider coverage.

Radiation Pattern

Every antenna has a different radiation pattern. The radiation pattern of a hypothetical isotropic antenna at 0 dB gain is a nearly perfect sphere in both the vertical and horizontal axes.

A standard omnidirectional 3 dB rubber duck antenna, for example, shows significant signal loss at the top and bottom (90/270 degrees). A similar radiation pattern applies to most omnidirectional FPV antennas.

As you can see, the gain changes depending on the direction you look at it. So, when we speak of an antenna’s gain, we really mean its maximum gain in a certain direction. In a 3-dimensional view, this radiation pattern looks like a doughnut.

Below is a directional antenna with 8 dB gain (a patch antenna). As shown, the majority of the signal focuses in one direction, with limited range in other directions.

Summary

While higher antenna gain can increase range, it isn’t always the best choice and should be matched to your specific use case and goals. As a summary, here are a few key points for you to remember:

• Antenna Gain Basics: Antenna gain doesn’t simply amplify radio signals; instead, it changes the radiation pattern, involving a trade-off between range and coverage. An ideal isotropic antenna (0 dB gain) radiates signals equally in all directions, but real antennas focus their signals more strongly in some directions than others.
• Directional vs. Omnidirectional Antennas: Omnidirectional antennas typically have lower gain (0-3 dB) and radiate signals fairly evenly in all directions, like a doughnut shape. Directional antennas, with higher gain, focus signals in a narrower beam, increasing range in that direction but reducing coverage in others. The trade-off is that as gain increases, the beam becomes narrower, focusing energy in a specific direction rather than amplifying the signal.
• Use Case Considerations: Higher gain is not always better. For example, in situations where wide coverage is more important than long range, a lower-gain, omnidirectional antenna might be more suitable. Conversely, for applications requiring long-distance communication in a specific direction, a higher-gain directional antenna could be the right choice.
• Practical Applications: The article uses analogies like a water balloon and a light bulb versus a torch to explain how energy is distributed differently with varying antenna gains. It also mentions using diversity receivers, which combine multiple antennas to optimize signal strength by selecting the best signal from different directions.

When deploying or optimizing gateway antennas, understanding antenna gain and its impact on range and coverage is vital. Whether you choose an omnidirectional or directional antenna, make sure it aligns with your network’s needs. By carefully considering these factors, you can enhance your IoT network’s performance and reliability.

Ready to optimize your network with the right LoRaWAN gateway? Contact the TEKTELIC team for a consultation at info@tektelic.com