Carrier and FCC certification are major milestones toward getting a new device to market on time and on budget. One tip for passing certification on the first attempt is to take a holistic view of how all the RF components work together to meet operator and regulator requirements.
The device design process typically starts with identifying the countries or region(s) where it will be used. The next step is choosing the mobile operator with coverage in those areas — or multiple ones if the device will be used in several countries where no single operator has service.
Each 4G and 5G technology has a unique set of capabilities, such as uplink and downlink speeds, latency, bill-of-materials (BOM) costs, and battery life. This also affects operator choices because device OEMs, systems integrators, and other product developers focus on ones that support the technology that their application requires.
Operators frequently allocate certain bands for each type of technology. For example, AT&T requires LTE NB-IoT or Cat-M devices to have modules and antennas that support bands 24 and 12.
These decisions determine which modules and antennas can be used because both components must be able to support the bands where each operator holds licenses. But this relationship sometimes creates the false impression that if the module passes operator and FCC certification, then the entire device is automatically certified. It’s easy to make this assumption because many module vendors market their products as certified for use not only with certain operators, but also on specific networks, such as AT&T’s Cat-M and NB-IoT networks.
This caveat highlights the importance of understanding how the module and antenna work together. In fact, module manufacturers specify the peak gain limits for antennas used with their products. With embedded antennas, for example, the ground plane, the components surrounding the antenna, and the device housing all affect gain. (For a deeper dive into the fundamentals of gain, see “Understanding Antenna Gain and How It Affects Device Performance, Reliability, and Competitiveness.”) Navigating these requirements can be complex, which is why device OEMs frequently turn to Taoglas for guidance.
Understanding Efficiency and Power Requirements
Each carrier has its own minimum antenna efficiency requirements for the bands where it holds licenses. If the antenna’s ground plane isn’t sized properly to meet an operator’s efficiency requirements, then the device won’t be certified for use on its network. This is an example of how the operator’s band choices affect product design.
With both embedded antennas, the ground plane is one of the factors that affects total radiated power (TRP) and total isotropic sensitivity (TIS). Each operator has its own set of TIS and TRP requirements, which vary significantly by band. Hence the importance of choosing an antenna capable of meeting the carrier certification requirements for each operator in each band that the device will use.
Some external antennas don’t require a ground plane. If they use a cable longer than 20 cm, they don’t need to go through carrier certification.
Most modules output at Power Class 3 (23 dBm), while low-power applications typically use Power Class 5 (20 dBm) modules. In the U.S., each type has its own set of requirements, which vary by band and by operator. The following example is for an LTE Cat-M1 device on AT&T.
Flexibility for Future Proofing
The device’s longevity is an additional consideration. For example, some devices are designed to remain in service for a decade or longer, such as smart utility meters. The longer the service life, the more likely that the operators in a given area will have coverage and tariff changes. If the business model will give users or their service providers the ability to switch operators in the future, then it makes sense to choose a module with an electronic SIM (eSIM), which can be updated over the air with a new operator’s profile.
In those cases, the antenna needs to be able to support not only the bands used when the device is initially deployed, but also the ones that potential future operators use. For example, the antenna should support both AT&T’s Band 12 and Verizon’s Band 13 to ensure network access when switching operators.
If future proofing is important, then these aspects need to be considered early on in the design process, when the module and antenna are being chosen. If either or both do not cover all of the target bands at launch and five or 10 years later, then the device won’t pass carrier certification. That means devices already in the field will be unable to switch to the operator with better coverage, performance, or pricing. This limitation could create opportunities for rivals to offer those users that flexibility by switching to their product.
How Pre-Certification Helps Ensure Successful Certification on the First Attempt
Once their new device is complete, OEMs can submit it to operators and the FCC for certification, which includes lab testing and field trials. But it’s highly advisable to go through pre-certification first.
This process identifies potential issues so they can be addressed before the product is submitted for operator and FCC testing. It increases the likelihood of passing all of those certifications quickly and thus avoiding the time and expense of redesigns and resubmission. By avoiding certification delays, pre-certification helps OEMs get their product to market on time and on budget. (For a deeper dive, see “Why Cellular Pre-Certification is Critical and How to Successfully Navigate the Process.”)
Device OEMs also can leverage Taoglas’ experience integrating antennas with a wide variety of module vendors. To learn more, visit https://www.taoglas.com/taoglas-antenna-reference-guides
