Five ways to win at antenna integration

Antennas are fundamental to the performance of connected devices, but are often implemented as an afterthought, resulting not only in sub-optimal performance, but also in less-than-ideal form factor. It can also have a negative impact on cost for the device as a whole. It is therefore essential that organisations prioritise antenna design as part of a holistic device design philosophy – bear in mind that it is practically impossible to fix bad antenna design. Early decisions need to be made regarding the relative merits of embedded or external devices and then attention can turn to optimising antenna integration.

Here are five important antenna considerations that will help you maximise the performance, optimise the cost and minimise the form factor of your connected IoT devices:

1. Recognize that all parameters are crucial and interact together. Place equal importance when designing on return loss, radiation pattern, efficiency, gain, and antenna polarization. By assessing all of these with equal attention you will be able to find the optimal balance and set the basis for a successful antenna design.
2. Focus on the architecture and position of the antenna within the device. Antennas must be positioned with care. Proximity to other components and metals will cause interference, limiting performance. An easy way to ensure optimal positioning is to follow the reference design in the antenna vendors data sheet. The main challenge here is to balance the best position for the antenna with competing needs of other components along with the overall size of the product.
3. Prepare to address detuning challenges. All embedded surface mount device antennas are vulnerable to being detuned by the customer’s device. The app’s PCB, the dielectric housing, the battery or LCD, and the surrounding components can all cause detuning. Detuning effects can be compensated for with a matching circuit that is placed on the host PCB, close to the antenna feed point. It is recommended to utilize a matching circuit of at least four components.
4. Establish certification criteria at the start. Certification takes three main forms: regulators, telecoms industry and operator certifications. Some or all of these must be complied with for the device to be approved for use, depending on region. It is important to understand the requirements of each because they can have impacts on device design. For example, T-Mobile’s utilization of the 600Mhz band in the US requires longer ground plane lengths for embedded antennas. Therefore, set a performance target at the start of the project and always design with some margin to ensure certification can be achieved.
5. Select IoT modules and antennas from the same supplier. The module can’t work without the antenna and vice-versa, so purchasing both from the same supplier simplifies the design process, gives you engineering support from one team, enabled easier pre-compliance testing and accelerates time to market.