Regarding nRF51822 Proximity Range

[Nazmus Sakib]

Hi all.

I am making a custom PCB with nRF51822 SoC. For my project I need to achieve long Proximity range around 350 Feet. Where my Board will communicate with iPhone.

I know to get max range good Antenna RF tuning is needed and in this Developer zone there are some more related discussion. I reviewed those.

I have some queries:

• Is it really possible to get around 350 Feet range using nRF51822?

• Which antenna type will be best choice? Chip Antenna or PCB trace? Though there are several types of PCB trace like Inverted-F-Type and some other.

• In BT classic theory power Class (1,2 and 3) is an issue where I know Class 1 can give more than 100 meeter. So in BLE Class (1, 2 and 3) also involved? I can not use Class 1 and my Board need to be low power running from regular Cell Coin Battery.

I found some Module. Example RFduino. And its memento it can support few Hundred feet. But the Module uses Chip Antenna.

Please suggest me what is the way to get best range with minimum power consumption.

Thanks in advance.

Regards.

[Janek Mann]

Hi Nazmus,

When a module like the RFduino mentions that kind of range you can be certain that it is only under ideal conditions (in freespace, direct line of sight, no walls etc). If your application allows it, a directional antenna would help a lot (but needs to be evaluated carefully from a regulatory point of view).

The NRF51822 can manage connections at that range, but not consistently, in my opinion.

Most chip antennas are actually no better, or worse, than a good PCB antenna of larger size, so that wouldn't help much unless you have size constraints (like the designers of the module used by RFduino did).

Another issue to keep in mind that for a proximity application, the accuracy will be extremely poor at higher range. In other words, you may have a reasonable connection at one spot 350 feet away but no connection at all a foot to the side (or even a foot closer to the iPhone), due to constructive / deconstructive wave interference.

[Nazmus Sakib]

Hi Janek.

Thanks for your feedback.

Yes 350 Feet I mentioned considering Line Of Sight.

My board have size constraints. For antenna my available room is around 10mm X 5mm (W X L). In this case, PCB antenna can be used? Or better Chip antenna?

Well, 350 Feet will be best for me. But if device can work with 250 Feet that will be fine for now.

My need is to measure the Proximity RSSI and show an approximate distance (between device and phone) on iPhone.

if you have any recommendation on Antenna (PCB or Chip), please advise.

Regards.