RF aspects with Kicad

Projects
1

Hello,

@maui Thanks for the information is helping me a lot.

The manufacturer of GPS / GNSS module made a Design Review Report and i need to insert a matching network between the module and the antenna to 50 ohm.

it can be calculated with PCB calculator?

I am using 4 layers and have not yet made any trace.

I try to connect this module http://www.telit.com/fileadmin/user_upload/products/Downloads/GNSS/SL869/Telit_Jupiter_SL869_Hardware_User_Guide_r2.pdf , page 21

with this antenna http://www.abracon.com/patchantenna/APAE1590R2540AKDB1-T.pdf

2.1. Schematic review

2.1.5. RF aspects
For a better antenna operation, insert a matching network between the module and
the antenna.

2.2. PCB Layout review
2.2.1. General placement
Improve the routing of the tracks on the PCB. The differential tracks of USB signal
should be 90 ohm.
2.2.2. RF aspects
The track between the module and antenna should be 50 ohm.

Best regards

2

there is a tab just for TransLines ā€¦

you can get some extra info @
https://www.maximintegrated.com/en/app-notes/index.mvp/id/5100
and here some AD slides
http://www.wdv.com/Electronics/Fab/PCB%20Layout/HighSpeedPCBLayout.pdf
there is also a branch version of kicad featured for RF


you need to build it but it is working with nice RF featuresā€¦ (stitching vias, via shielding and solder clearence)

anyway Iā€™m a noob too in RF so Iā€™m hoping some RF guy could help you a bit more :slight_smile:

3

Most commercial PCB suppliers donā€™t guarantee Er for their FR4 material, depending on the resin/glass mix.
Start with a guess of 4.5 at 1.6GHz

Fortunately 1.6GHz is not particularly high, so just avoid very long RF traces and you should be OK

1 Like
4

Hello!,

Thanks for the replies!

The distance between RF pin and antenna pin is short.

You think that is better a Roger? http://www.rogerscorp.com/acs/producttypes/9/RO4000-Laminates.aspx

I want to share the project on github but I hesitate for a license, GPL v3, LPGP v3, MIT, Apache ?Āæ

Greetings!

5

RF specific laminates are better, but expensive and limit PCB suppliers. For a GPS/GNSS module FR4 should work OK. The exotic laminates are for higher frequencies or ā€œprofessional/militaryā€ uses where reducing insertion loss by 0.5dB is worth spending money