Antenna design for wearable nrf51822

[atb08]

Hi All,

I am currently working in a team desigining a wearable that uses BLE in 2.4 GHz band to communicate with smartphones and other devices. We have been working with an nrf51822 chip as our BLE controller coupled with a balun and chip antenna and have had mixed results thus far. As it is a wearable device that is worn close to the skin, we would be interested in knowing if a trace antenna would offer better performances? Especially as it would also provide a gain in terms of space.

Many thanks in advance, it has been a real pleasure using the devzone and provided documentation during the development process.

[Dave_couling]

As for bandwidth, you want a wide bandwidth antenna. Each human body will shift the Antenna differently. Having a wide bandwidth will assure that the antenna response will be within the BLE frequency range.

Inverted F trace antennas have quite good bandwidth and are a good option for this application. Much better then 99% of chip antennas. However chip antenna's can be more immune to human body detuning.

In summary, a good trace antenna (Inverted F) that is tuned properly in its application environment (on Human Body) can have good performance.