Regarding of GPS and LTE antenna Connection for nRF9160

[chirag.aumraj]

Hi,

We develop a GPS tracking device.

Development kit shows two type antenna, an external antenna(With connector) and onboard antenna for GPS and LTE.

We won't use an external antenna for our application due to the compactness requirement. 

• Can we use a passive antenna(Onboard antenna) without an external antenna? 
• Does any power supply required for a passive antenna?
• It would be helpful if you suggest recommended balun and PI circuit for both antenna.

Waiting for your kind response.

Thank you,

Chirag 

[Andreas]

Hi,

 

• Yes, a passive antenna can be used.
• No power supply needed for the antenna itself. With a passive antenna you might want a on-board LNA, if so this will need power supplied. (active antennas have LNA built in, this is the part that needs the power supply.
• No balun is needed. Pi network for matching will depend on the antenna, your board layout etc., it will have to be measured and adjusted for your specific board. Until you do so, you can just leave it unpopulated or use the components suggested by the antenna manufacturer.

 

Best regards,

Andreas

[chirag.aumraj]

Hi Andreas,

Thanks for your quick response.

Is it possible to use a passive antenna without LNA? for our compact device.

But in nRF9160 development status shows that onboard passive antenna does not work on DK.

https://devzone.nordicsemi.com/b/nrf9160-development-status/posts/nrf9160-development-status

If you suggest recommended a passive antenna without LNA it would be helpful for us.

Best Regards,

Chirag

[Andreas]

Hi,

 

Yes, it is possible to use a passive antenna without a LNA, but note that performance will be worse. How much worse is hard to say, and you need to test it in your specific board for you specific application. Typically without a LNA might have to be closer to a window or even outdoors to get lock.

 

The link says that the GPS functionality is poor on the DK because the antenna is incorrectly matched, not because it is passive.

 

You should choose an antenna which has ground plane size and shape requirements which correspond with your PCB, and specifies a PCB layout which you are able to replicate. If you do not replicate the mounting specifications given by the manufacturer you can not expext optimal performance.

 

Best regards,

Andreas