NRF9160 cellular antenna design or selection

[sawaiz]

Hello,

We are looking for options for antennas for our nrf9160 application. We have made prototypes with the U.FL connector and the cabled patch antennas that are common as well as the PCB antenna used in the DK. We are trying to find the optimal antenna option that will provide the best SNR in our environment.

Our sensor is placed in the basement of homes near pipes and electrical equipment providing large ground planes, shielding, and will be variable from installation to installation so we are concerned about power consumption and connectivity issues with not a good SNR.

In the past for projects on 2.4Ghz or 868/915 mhz devices I have used PCB trace antennas that are designed and tested and published buy TI or Cypress. We could also test PCB antennas with a U.FL cable on a daughter board with its matching network. Would PCb antennas even be a viable option for cellular?

Does anyone have good resources for similar options for cellular antennas? Size and price are secondary to performance at the moment but having multiple options that can be tested is best. RF design is not my strongest suit, is there anything else we should be looking at or doing besides tuning matching circiutry?

Regards,

Sawaiz

[ketiljo]

For cellular use, you will need to design an antenna for two or more bands and that is a proper challenge with PCB antennas. Unless you can do antenna simulations, PCB antennas are really not an option for cellular. 

You could look into a chip antenna, like the on the nRF9160-DK. But this needs a relatively large ground plane to perform properly. For smaller designs, it's better with a external dipole antenna that's not dependent on a ground plane. 

External antenna, which you connect with a U.FL connector or similar, is matched on the antenna side of the coax cable. So you should not do any matching on the PCB here, this will only create mismatch in the cable. 

Obviously, try to separate the antenna from the metal pipes as much as possible.