Design circuit external passive antenna GPS for nRF9160

[Lukas Gabriel]

Hi,

I would like a circuit recommendation with LNA to connect an external passive gps antenna? Is it possible to use an external passive antenna with nRF9160 or is it more recommended to use only an external active antenna for GPS? Because in the project I am developing in the RF range, there are capacitors for DC blocking (intrinsic safety), so the active external antenna option would not work, what would you recommend in this case for the GPS circuit with external antenna?

[JONATHAN LL]

Hi,

Check out the Guidelines we have on the nrf9160, but e do have GPS interface and antenna section. There is a active antenna alternative there that you can consider and the LNA alternative.

Regards,
Jonathan

[Lukas Gabriel]

In that case, could I connect a passive external antenna to J1, that will work without problems? C1 and C2 are the capacitors for DC blocking (intrinsic safety) that I had mentioned, because of them it is not possible to use the active antenna option.

[JONATHAN LL]

Using a passive antenna on J1 is ok, but i wonder what the reason for the U1 placement is. I would recommend to move U1 to before the LNA similar to how its done on the nrf9160DK un less you have a specific reason. 


As for the tuning of the GPS antenna, it should be done close to the antenna and not before the connector. 

Regards,
Jonathan

[Lukas Gabriel]

The U1 component is to be connected to the VNA (Vector Network Analyzer) 
for the impedance matching of the RF track.Thank you very much, I will
make the changes you recommended.