Why is the antenna the most critical component of my design?
Looking at the different elements that impact the quality of Sigfox connectivity, the device antenna is actually the only parameter that can drastically reduce the link budget (and therefore device connectivity) and that you can have an impact on as a device maker.
Sigfox base stations are installed in such a way that in normal conditions, the Sigfox Network ensures excellent coverage. Coverage is continuously being optimized and improved. Between the device and the base station, some propagation effects may impact the link budget and in most cases, not much that can be done about this. For example, if your device is installed on a shop door and a big truck parks right in front of the door, it will automatically change the propagation conditions.
This type of situation is taken into consideration in Sigfox's network deployment and supported in most cases. From a device perspective, most RF transceivers provide the recommended power level (14 dBm or 22 dBm). Therefore, the only parameter which can decrease device connectivity and on which you can have an impact is the device antenna quality.
This is why it is important that the radiated performance of your device be optimal and thus that the Sigfox antenna for your device is well designed and implemented.
An antenna is not a standalone component but uses and interacts with all other components/physical parts of your device. Therefore, in order to succeed in your device antenna integration, you should consider it at the beginning of your device development. The earlier you start considering the antenna in your device development the more chances you have to end up with a high-quality product.
Because an antenna is impacted by its close surrounding, it is important to select the right antenna solution according not only to your device architecture, but also to the way the device will be installed and used.
Once your device is designed and certified, it is also important to make sure that the way the device is installed does not decrease its radiated performance.
In short, optimizing the antenna design for your device and its use case as well as making sure that your device installation does not reduce its radiated performance will have a huge impact on the Sigfox connectivity quality.
So, simply put: hire an antenna specialist early in the project. Since antenna design/selection can have an effect on battery consumption for example, you may not meet your project requirements if you hire a specialist too late.
Using a custom-made antenna should seriously be considered to obtain maximum radio performance from your device. However, a lot of off the shelf antennas are readily available on the market and can be integrated into your device.
Antennas can be designed in many different ways, to match the variety of use cases on the market. They can be very different in terms of size, form, and integration, but also in terms of performance. To ensure the maximum radiated efficiency of your device, be sure to choose one that fits your environment, your use case, and your coverage needs.
For an overview of all companies designing antennas, please consult the Sigfox Partners Network and Mouser (example for 868 MHz) or Digikey for an idea of the form factors available in the market today.
Please note that all these off the shelf antennas are designed to be used in particular use cases and may not be compatible with yours. In some cases, they are optimized for a specific device form factor. Antennas are also optimized for specific frequencies, so be sure to select one compatible with your radio zone.
Most antenna manufacturers provide support to select the best antenna for your specific device form factor and use case. Do not hesitate to contact them.
In order to help our ecosystem to develop antennas, a white paper which details several aspects of antenna design and integration is available. You will find ideas, good practices and advice on what can and cannot be done while designing your antenna.
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Please find below an example of an antenna designed by our very own experts for the Sens'it 2, our multi-sensors device developed in close collaboration with our partner Axible.
We designed this device as an example of what can be done with our technology, and we decided to open source the design of this antenna to inspire other device makers.
This antenna can operate in all of the major Sigfox radio zones (from 868 to 923 MHz) and can be easily reused in other devices that have a form factor similar to the Sens’it's. The integration guide below will help you integrate and adapt the Sens’it antenna to your device.
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Again, hiring an antenna designer is the best early investment you can make for your IoT project. Here are a few names from the Sigfox Partner Network: