Hi,
I want to know what kind of antenna nordic recommend to use with NRF52 chips.
Please could you guide us about it. We are interested in some sort of table where we can check and compare the antenna sensitivity.
In our application, we need good antenna with good sensitivity.
Nordic generally recommends you follow their reference design. Most of these utilize meander, monopole or F-meander hybrids. When we discuss following their reference design this means copying it precisely.
With RF devices even a 1mm change in a component position or a small change in the ground flood on the board will have a huge impact on the match and ultimately the antenna performance.
You should start by looking at various reference designs for bluetooth chip antennae and choose something in a form factor and price point that suits your product. Most of the chip antennae will have a nominal gain of around -2 to 0dBi. It is important to note that many vendors specify peak gain. Peak gain is only available in a small arc around the antenna. Quality chip antenna vendors will provide radiation pattern plots to help you figure out the actual gain you will get.
In order to get the performance the antenna vendor specifies you must provide for a ground plane and antenna position per their reference design. The engineering skill comes from your ability to get the nRF solution to fit into something that allows the antenna to work well.
Even under the best of circumstances be prepared to do some matching work with a VNA (vector network analyzer). While it might seem to someone new to RF design that it is a simple matter of hooking up components to make a perfect match...it is not. All designs are highly influenced by their local environment. Epoxy, glass, grounding, vias, trace thickness and width. Even changes as little as a fraction of a millimeter will change the match required for the antenna and the nRF to work well together.
Here is a recent post from Nordic on the subject: devzone.nordicsemi.com/.../
Can you send me link of their reference design for antenna ?
Do you know where I can find information such as radiation pattern information for this ?
The antenna reference designs I referred to would be the vendors reference design not Nordic's. Again Nordic uses printed pcb antennae.
You should start by going to Digikey, Mouser or some other component distributor of your choosing. Just search bluetooth chip antenna and use their filters to screen for items of interest.
As I said the better antenna vendors will provide radiation plots on their website along with reference design artwork. The artwork will terminate into a 50 ohm microstrip. The engineering work comes from integrating the Nordic solution into the antenna solution.
There are many chip antenna vendors. Johanson Technology, Taiyo Yuden, TDK and Pulse come to mind quickly. But there are many more.
As you mentioned that there are several types of BT antenna by different vendors so how can one decide that which one is better for his / her use case? What parameters one needs to check while selection particular antenna for our use case?
That really is the question, "What is your use case?"
You need to determine whether your device is mounted in something, on something, worn on someone, held by someone, etc.
Then what is is talking to...a computer, a smartphone, another BLE device.
How much range does it really need? Big difference planning on 100meters vs. 1 meter.
What type of housing will it be in? RF energy propagates well through most plastics, but will not pass through metal.
Finally based on the above, how much space can the PWB occupy? A big factor for antennae is the size and shape of the ground plane. Inevitably the ground plane is your logic, power and wireless SoC solution. You need to accommodate your layout such that the logic, power and wireless SoC ends up looking like the ground planed specified by the antenna vendor.
At this point only a few antennae will meet your products requirements.
