Knowledge is power, as they say. When building a wireless product, understanding and preparing for certification requirements can help optimize your design from the beginning so you can pass certifications on the first attempt. This article will cover the key certifications to prepare for as you begin planning your product design.
Any product to be sold in the U.S. must pass FCC certifications, which include the following:
Non-linear power amplifiers in the transmitter chain can generate harmonics which are then radiated by the antenna.
Non-linear PCB components can pick up the fundamental frequency radiated from the antenna and then generate and radiate the harmonics of the fundamental frequency.
Cellular over-the-air (OTA) tests are required for cellular designs with antennas located less than 20 cm from the radio, and are very challenging to pass. Cellular certification testing often includes the following, depending on carrier selection and geographic region:
RF Engineering Manager, Kyle Sporre, summarizes PTCRB test requirements, and the regions where they are applicable in the simple whiteboard video session below.
It is very important to understand the design principles that affect certification testing early in your process and to apply best practices. Effectively controlling noise prior to performing radiated cellular tests such as TIS and RSIC can help you achieve the low EMI required to pass certification testing. TIS requires even quieter PCB emissions than FCC certifications, and failures caused by noise coming from the host electronics are common.
Note that products that do not include an antenna within 20 cm of the device are not subject to OTA tests. For example, this includes box products with an antenna port that requires the customer to supply the antenna, or products with cabled antennas that are more than 20 cm from the device. To ensure success, design your product up front with certification requirements in mind. If you need assistance, Digi's Wireless Design Services (WDS) team can help with your product design, or even correct design issues that can lead to certification failures.