Chip Antenna selection and PCB eagle files

[Asaxena]

Dear Nordic Team

can you please help me select the correct and available Radio Chip Antenna for Bluetooth communication. 
also, can you please point me to the Eagle files of sch and board for copying the RF trace lengths, width and L1-C3 values?

I am using NRF52832-QFAA-R7 chip for developing a medical device that measures knee progress in physiotherapy patients.

[Kaja]

Antenna choice is complex and depends on many factors including technical and commercial considerations. We have some reference designs, and I can describe some of the options for you:

Monopole, printed PCB antenna: This is easy to make and easy to tune, you also only need one impedance matching component, so it’s cost effective. Here the spacing is the issues, you need to make it about 23 mm long needs a minimum of 5 mm clearance to the ground plane. High bandwidth, making it fairly resistant to detuning. Link to our whitepaper: https://infocenter.nordicsemi.com/pdf/nwp_008.pdf?cp=12_18

Meander antenna, printed PCB antenna, ex. our dongle antenna design: Requires a smaller area than the monopole antenna, but usually requires a pi-network for tuning in addition to length. Lower bandwidth than a quarter wave monopole antenna. Here is a link to our nRF52840 Dongal design files as an example of this: https://www.nordicsemi.com/Software-and-Tools/Development-Kits/nRF52840-Dongle/Download#infotabs

 

Chip antenna: Higher BOM, but the antenna is small. The downside is that it usually has less gain. It requires a matching network, based on the vendors recommendations. It has a lower bandwidth than a quarter wave monopole antenna so it can be sensitive to detuning.

Considering your target of a very small form factor a chip Antenna makes sense but reducing antenna size most often results in reduced performance. Some of the parameters that suffer are:

• Reduced efficiency (or gain)
• Shorter range
• Smaller bandwidth
• Distorted radiation pattern
• More critical tuning
• Increased sensitivity to component and PCB spread
• Increased sensitivity to external factors (“body” effect, ground plane etc.)

It is often better not to reduce antenna size too much, if you can avoid it.

As a rule we do not recommend specific chip antennas. The selection will depend very much on the end application design, but you can ask the antenna vendors to assist you on choosing the right antenna for a specific design, for example Johanson has a useful tool that helps with this selection: https://www.johansontechnology.com/chip-antenna-selection

We don't have Eagles files, we have altium and gerber files.. this can be found under downloads on the product page on our web site. 



Also note: We offer to do HW review, so feel free to create a review ticket, when you have a design you want us to reveiw.

Best regards,
Kaja