QUESTION

Question

Hello,

I have a project for an IoT device with 83mmx40mm PCB size.

We have LTE with GNSS in the same modem and LoRa communication (868MHz).

How could I start search for antennas for coexistence of this 3 bands (GSM, GNSS and LoRa).

I would need PCB antennas to achieve clients requierements for a small device to be hidden. So, we can't use external antennas.

I've been checking your SR4L034 that seems a good option for GSM, but what bout placing other antennas for GNSS and LoRa, what should be the best placement?
I would apreciatte any PN suggestions and getting guidelines for placement and routing on a 4 or 6 layers PCB.

Thank you.

Best regards,

daniel

Answer 1

Hi Daniel,

Our Pharaoh antenna would be better for LTE on small ground plane than the Inversa. For GNSS you can use the Sinica antenna. Pharaoh antenna would also cover LoRa depending on the module, you could use single Pharaoh antenna or use 2 Pharaoh antennas. The placement for the Pharaoh antenna is on the short edge and Sinica on the Long edge.

A 4 layer PCB will be good and flood copper in any unused areas of each layer.

Best regards,

Yu Kai Yeung

Comments

Hi Yu,

Thank you for your fast reply.

Ok. I will check PN you mentioned and try to get information from there. If there is any question I will comment to you.

I guessed as Pharaoh is covering the band of 868Mhz but I don't know how to route the 2 outputs of modem and LoRa transceiver and share an antenna.

Should not be better to have a dedicated 868Mhz and get more efficency antenna?

We are using SEMTECH SX1276 transceiver.

Thank you for your support!

I really appreciate it.

BR,

daniel

---

Yu,

Ok, I think finally I'm going to use:

1. Pharaoh for LTE

2. Sinica for GNSS

3. Grandis for LoRa

So, as you said LTE antena short PCB edge, so along the 40mm egde, Sinica on the long PCB edge, so along 83mm edge, and Grandis other side of the 40mm edge. 

Once I have the placement I can share it with you, so you could give your opinion.

Thank you.

BR,

daniel