I have been tracing PCB for the first time and came to a few questions regarding GPS antenna selection and placement on PCB.
Basically, I am trying to make as small as possible PCB with GPS/GSM modem. On the top layer, I placed a GPS antenna, on the bottom - GPS/GSM modem. PCB is 30 x 30 mm size.
- Can I place GPS/GSM modem directly below GPS antenna or should I move modem to the opposite side of PCB as much as possible? (I worry that there will be GSM antenna traces directly below GPS antenna).
- Now I selected 25 x 25 mm GPS patch antenna. Should I select smaller antenna (18 x 18 mm) to have more space for better placement of modem (not directly below GPS antenna)? What is better: bigger antenna but modem directly below GPS antenna or smaller antenna but the better placement of modem?
- As I understood, in order to get the best performance, the entire layer with GPS antenna must be plain ground. But what about inner layers (2nd and 3rd)? Should it be etched below antenna or it is better to make there ground pads too?
Thank you in advance for your time answering questions.