nRF52840 Dongle Antenna Simulation in CST

RE: nRF52840 Dongle Antenna Simulation in CST

Radio — Tue, 11 Aug 2020 16:26:13 GMT

Many thanks for the support given.

RE: nRF52840 Dongle Antenna Simulation in CST

Kaja — Tue, 11 Aug 2020 13:02:29 GMT

If you would like you design files to be confidential, then yes; you should do this in a private ticket.

Best regards,
Kaja

RE: nRF52840 Dongle Antenna Simulation in CST

Radio — Tue, 11 Aug 2020 09:37:57 GMT

Hi,

This should be done by opening a private ticket?

Thanks!

RE: nRF52840 Dongle Antenna Simulation in CST

Kaja — Tue, 11 Aug 2020 09:35:55 GMT

Hi,

so we first do a design review, when the design look okay you can send us two working boards and one enclosure.
At the lab we do RF measurements and tune the radio matching components and crystal (32 MHz) load capacitors.
We also tune the antenna, components (and length, depending on the antenna type).
Then we send you an report with the results, and suggest components values.

Best regards,
Kaja

RE: nRF52840 Dongle Antenna Simulation in CST

Radio — Mon, 10 Aug 2020 08:23:28 GMT

Hi Kaja,

Thanks for the reply. May I know what is the procedure to do the matching service?

Thanks!

RE: nRF52840 Dongle Antenna Simulation in CST

Kaja — Mon, 10 Aug 2020 08:15:54 GMT

Hi,

I would recommend you to copy the design form the dongle, and then leave the components in the matching network for the antenna NC and with a 0 Ohm resistor.
It's must easier to tune the components values on a physical board, then it is to simulate it. We offer to do this service for all our costumers.

Same with the radio, copy the reference design, then we fine tune the components values for the specific design.

Best regards,
Kaja

RE: nRF52840 Dongle Antenna Simulation in CST

Radio — Wed, 05 Aug 2020 12:33:09 GMT

Hi Kaja,

Yes I first want to simulate the existing nRF52840 dongle antenna with the substrate definitions Nordic has used. Then use this simulated S-parameters to match to the chip impedance and compare with the matching network in the given nRF52840 dongle schematic.

Reason to do this is because, based on the manufacture, my PCB specifications might change. So then I can do a re simulation and have a feeling on the results, based on the substrate I am going to use to manufacture.

Further note, I did a simulation including the entire ground plane according to the chip size. I also had to include the CPW feeder that connects to the ground. I was able to get a better result now.

However, If I don't include the CPW feeder I get bad results. I am not sure why this is so. Also Waveguide port dimensions have significant effect on the response as well. Please see the attached images.

Thanks!

RE: nRF52840 Dongle Antenna Simulation in CST

Kaja — Wed, 05 Aug 2020 12:18:00 GMT

Hi,

what do you want to simulate?

Are you trying to simulate the antenna, so that you can find out the components values for the matching network?

Best regards,

Kaja

RE: nRF52840 Dongle Antenna Simulation in CST

Radio — Tue, 04 Aug 2020 11:59:12 GMT

Hi,

In my above simulation, it does not have a ground plane. This is the reason why the results were wrong. In the nRF dongle, RF feeder line width is 35 mil which I think had calculated as a CPW. So I added a feeding CPW Microstrip line to the antenna with width 35 mil. Now I am getting some what sensible result, but the return loss is still not very good yet.

Below please see the images of the new port configuration and the results. Any idea what I am doing wrong. I am also getting some warnings while running the simulation.

Thanks!