QUESTION

Question

I am using GPS L70 Module from Quectel,& using the part M20057-1. Link has design details. Currently, I have shorted AT1 & AT2 with 0-ohm res. I feel no Antenna tunning is needed since with the same RF path GPS is working with External u.fl active antenna. What could be a potential issue that am not able to fetch any HDOP, PDOP values or any satellite details from this module. ? PCB Stack-up is fairly simple. with L1-L6 removed GND plane below this module & RF path is 50 ohm Impedance matched.

https://drive.google.com/drive/folders/11qm0c86zWnheqJYQzjyg3AhMalWw9MmD?usp=sharing

Answer 1

Hello Viral Vasa,

AT1 should start with a 1.8nH inductor and keep the AT2 as a 0 ohm resistor. To ensure the antenna is tuned properly I recommend placing a semi rigid coax on the trace just in front of the SAW filter on the M20057-1 after lifting the component just before the SAW filter to ensure the antenna is still tuned to 1575MHz. Sometimes placing the antenna in your plastic housing will shift the frequency lower and AT1 will need to be adjusted to re-center the frequency.

We offer our services to help tune your board if you are interested. Simply contact our sales@antenova.com to request this service.

Best regards,

Geoff S.