CC1310: CC1310F32RHBR Integrated loop antenna

A loop antenna for a key fob will have a very small bandwidth due to the physical size at 315 MHz and the final design and tuning will also be dependent on the key fob casing material.

Can you share you antenna measurements and layout ? 

Thanks for your reply

Here I've attached the Antenna dimensions and layout for your reference

Trace Length: 106.4989 MM

 Trace Width: 0.63MM

 Trace Height: 0.035MM

Regards

Elavarasan Thilagar

This antenna will have a small bandwidth of just a few MHz so the antenna matching will be critical due to the small bandwidth.

Have you measured the conducted output power first just to confirm that this is as expected ?

i.e.  disconnect the antenna completely and measure the conducted output power at the maximum power setting.

Thanks for your reply

We got -80 to -90 dBm as signal strength using Spectrum analyzer,

Will you give an example circuit for integrated Loop antenna design for the specific controller (CC1310F32RHBR)?

Best regards

Elavarasan Thilagar

Have you measured the conducted output power first just to confirm that this is as expected ?

 - This should be in the 14 dBm region for maximum output power setting.

Do not recommend to use a loop antenna since the bandwidth is so small that this will be sensitive and will need tuning.

Can you use a wire antenna such as PULSE W3126 ? https://productfinder.pulseeng.com/doc_type/WEB301/doc_num/W3126/doc_part/W3126.pdf

I would suggest the following instead:

Thanks for your quick response

Will try and update about working

Kindly confirm whether the below circuit will match or not

Yes this will be fine.

L10, C28, C24 & L11 should just be for the antenna match only.

Always measure the conducted output power first by removing C21 and measure at C21/C31 junction.

Do you have a VNA ?

We're having Spectrum analyser alone, 

Application's power is dBm is measured through Spectrum analyser only,

It is necessary to have a Vector Network Analyzer

Also by the following point you suggested 

"Always measure the conducted output power first by removing C21 and measure at C21/C31 junction"

We have that junction point of C21 & C31, as a testing point,

"How do we need to measure conducted output power at that point?"

"Please explain in detail."

Now we're updated like below mentioned TOP and BOT side of PCB

Blue color mentioned is Antenna

Kindly give your valuable feedback about this design

Regards

Elavarasan Thilagar

Hi,

Ideally, there should be no GND or components in the antenna region.

Why is there a GND ring around the antenna area ?

Actually, that is not s ground ring on the antenna, to pick up the best signal we found the copper holes from OEM board, so we replicated in our design

Hi 

For our application it is not suitable, Mechanical case is fixed already so we prefer a PCB antenna alone

we didn't have so much space to assemble the antenna suggested by you, Mechanical case for our application is already fixed