nRF9160 - Passive antenna for GNSS

PaoloZigoni

Hello everyone,

I’m using the nRF9160 feather for an asset tracking demo, I understand the board is made to be coupled with an active antenna, which unfortunately I cannot use in my project for mechanical constraint.

I need to use a passive antenna, do you have some tips on how to make it work properly? I would also make HW modifications on the fly if needed.

Thank you
Best regards

jaredwolff

@PaoloZigoni this may be tough as you’ll need an GNSS amplifier circuit along with a matched antenna. You could use something like this but I’m guessing since you don’t have room for an active antenna you will likely not have enough room for a passive antenna setup.

The nRF9161 Feather will have a combined antenna and onboard LNA. Stay tuned on that front.

PaoloZigoni

Thanks for replying Jared.
The problem is on the size and weight of the antenna. The ceramic module is too heavy and cannot curved.
I could easily add a tiny pcb on the feather, with the amplifier, and move from there with the flex antenna.

Maybe I could connect the PCB with LNA to the feather with a cable using the existing uFL connector, and then connect the antenna to this PCB.
Do you think it would work without making changes on the feather?

Thank you!

jaredwolff

PaoloZigoni you can totally do this. You will need to route power and ground to it as well. So 2 wires + 2 RF cables (in and out).

You also would need to figure out how to turn off the LNA when not in use. You could use the COEX0 pin but it would require some detailed soldering to the nRF9160 Feather. Otherwise a standard GPIO should do the trick too.

PaoloZigoni

Thanks, last question (sorry if it’s a noob question).
I have a ceramic GPS antenna that I got for testing, and just disassembled. I found PCB with (i guess) amplifiers and matching components.
Do you think that I could remove the ceramic part and solder the flex antenna to the antenna output? Could this work?

Best regards

jaredwolff

Possibly. You’ll have to experiment