What level of accuracy does your location application require: the size of a tennis court or the width of a paperclip? How long will your tracking devices remain in the field: a few years or over a decade? Where will they operate: in fields and highways or urban concrete canyons? And are your customers willing to pay a premium for accuracy, longevity, and resiliency?
Those are some of the top questions to consider when deciding whether to choose a dual- or multi-band antenna. Here are the primary differences:
- Dual-Band GNSS antennas support two frequencies, such as L1 and L2 or L1 and L5 in the case of GPS, or E1 and E5 for Galileo. When it comes to enhancing accuracy, availability, and resiliency, two are better than one because the application’s performance doesn’t depend on a single band. For example, if one signal is unusably weak, intermittent, or unavailable due to attenuation or other factors, the application has another to fall back on.
- Multi-Band GNSS antennas use at least three bands — such as L1, L2, and L5 — to increase the odds that the application will have enough usable signals even in areas where disruption is common. For example, the L2 and L5 bands are less susceptible to ionospheric distortion and attenuation by physical objects than L1. One reason is because L5 has the highest power of any GPS signal. A multi-band design that supports L2 and L5 is ideal for applications such as tracking cargo when the vehicles frequently are in areas where foliage or skyscrapers attenuate GNSS signals.
What Price Is Precision?
The cargo tracking use case highlights the importance of the end user price sensitivity question. The higher the value of their cargo, the more value they will see in an application that enables them to track its location with high precision — such as a few meters or less — even in challenging environments. This kind of requirement is one factor that makes the business case for choosing a multi-band GNSS antenna because end users are likely to be more willing to pay the premium price.
Some applications require high precision, such as 1 meter. In those cases, a multi-band antenna is essential because system performance increases when the module has access to more satellite signals. If the application requires even higher precision, such as centimeter-level accuracy, a subscription to an L-Band or real-time kinematic (RTK) correction service often is necessary. For more information about L-Band and RTK correction services, including their antenna-related considerations, see our blogs “How to Leverage the L-Band to Balance Accuracy and Affordability for GNSS Applications” and “Does Your Positioning Application Require Centimeter-Level Accuracy?”.
Of course, not every application requires continuous availability, 1 meter or centimeter precision, or all of the above. For example, pet trackers are a consumer product with consumer price sensitivity. Robot lawn mowers also are consumer products, and they typically operate in places with minimal foliage. In those cases, a dual-band GNSS antenna can achieve the right balance of performance and price to make the product successful.
The Value of Longevity
Longevity is another key consideration. Pet trackers, robot lawn mowers, fitness wearables, shipping container trackers, and bicycle computers all rely on batteries. A multi-band antenna can receive more signals and thus achieve more accurate positioning — and reduces device power consumption in the process if now the module spends less time and energy determining and reporting the location. But if the GNSS device has constant access to power — such as a vending machine — then a dual-band antenna may be sufficient because the battery is used only for backup.
Longevity also can be measured in terms of how long the device will remain in service. A multi-band antenna ensures that the device can take advantage of future GNSS technologies for additional performance. For example, constellation modernization projects are launching more satellites for L5 and L2 than for L1. (For a deeper dive into these projects, see “Navigating the L1, L2 and L5 Band Options for GNSS.”) The ability to support these new signals can be a powerful market differentiator for devices that users expect to remain in service for a decade or longer, such as tracking bulldozers and other construction equipment.
The GNSS antenna choice also is closely tied to the GNSS module choice. For example, if the module supports L1 and L2, the antenna also must support L1 and L2. Or if the antenna supports L5, it won’t help if the module doesn’t support L5. If the module is selected first, it automatically narrows down the antenna options.
To learn more about how to select the right GNSS antenna, speak to Taoglas’ Engineering team by clicking on the button below.
