What will happen if I bring the LTE antenna closer to the GPS antenna in nRF9160 DK 0.8.5 and reduce the isolation of them?

[Yusuke]

I read a nRF9160 DK 0.8.5 circuit design and have a question about the GPS circuitry.
What will happen if I bring the LTE antenna closer to the GPS antenna and reduce the isolation of them?
Does the GPS function work out?

Thanks

[cbd]

You run the risk of causing interference on both your LTE and your GPS. Admittedly most of the issues will be with the GPS, but you could get some odd harmonic back that may interfere with the LTE as it transmits.

As a rule you should aim to keep disparate antennas as far apart and as isolated as possible.

If in doubt there are companies that can advise you, including some antenna manufacturers, based on them running simulations using your layout gerber files.