QUESTION

Question

Hi,

I’m developing a smart pet collar that includes GNSS for positioning and NB-IoT/LTE for communication, using the nRF9160 SiP.

The PCB is quite small (about 30 × 45 mm), so using both GNSS and LTE antennas directly on the PCB isn’t feasible — the ground planed PCB size is too limited. It might only perform acceptably on the higher LTE bands, but I also want to support lower bands (600–900 MHz).

My current plan is to keep a GNSS antenna on the PCB, and use an external flexible LTE/NB-IoT antenna (possibly Affini, Mitis, or Armata) mounted around the collar itself, not in the casing of the PCB.

If I understand correctly, these flexible antennas are ground-plane independent, so the small PCB should not be a problem.

I’d really appreciate your guidance on a few points:

1. Which Antenova antennas would you recommend for this setup: one flexible external LTE/NB-IoT antenna and one PCB-mounted GNSS antenna on a small PCB?

2. How much does bending the flexible LTE antenna (for example 30–40°) affect its efficiency?

3. Since the device will be very close to the animal’s body, how significant is the performance loss likely to be? Can this effect be reduced by fine-tuning or matching components on the PCB?

4. Do you offer any support for measurements, tuning, or matching once I have a prototype?

5. How does coax cable length influence efficiency? Should it be kept as short as possible? Do you offer antennas with custom cable lengths?

Thanks in advance for your help and any recommendations!

Best regards,
András

Answer 1

Hi András,

1. For GNSS I would say Sinica for center edge mount or Agosti Corner mount. The LTE depends on the size of enclosure and bands required but Moseni and Mitis would be the standard for LTE.

2.Bending it does slightly affect the performance as it changes the radiation pattern

3. Yes, matching will help but it won't solve the problem. The antenna placement and cable routing of the LTE antenna will be very important. I unfortunately can't give exact number on how much will the performance drop as that will require some testing.

4.Yes, we can review your gerbers/STEP files to check for placement or any other potential issues before you create prototype which we can also test and match.

5.Yes, the cable does affect the antenna usually 1/4 wavelength length for the cable is good(around 110mm) this is on the longer side so the cable routing will be important.