I am working on a GPS based project. Unfortunately, all Ublox M8N modules you can buy on AliExpress are fake at the moment. I have already contacted the factories, but a version that runs version 3.01 is not expected. Unfortunately, because of this, I have to drop that version and look for another alternative. The new Ublox M10 module series is available on the market. However, there is no external antenna connection option on these, only what is on the motherboard is quite small. Until now, I used an external antenna with an SMA connector, like this:
I would stick to this solution so that an external antenna can be connected with an SMA connector.
The M10 module available on the market has a factory ceramic antenna on it. As I looked, it is fixed with tin in the middle, and on the other side of the board it is connected directly to one of the inputs of the M10 chip:
Could it work if I unsolder this and solder a plain SMA connector in its place, to which I only solder the leg of the internal signal and screw the external antenna onto it:
I don't know if I still need some electronics? I also don't know if these external SMA antennas are passive or active... if active, do I need something else? Has anyone tried it?
I definitely need a GPS module that knows GPS+GLONASS+GALILEO and uses UBX output messages, and I definitely need the SMA antenna connection as well.
GALILEO e.g. only the NEO-8M knows it, and only after firmware 3.01.
But that's not really my question, but whether the antenna can be solved this way... What is basically on the M10's circuit board is if everything is a true passive antenna. If I want to connect an active antenna, I don't know if 1 wire is enough?
Do you see the 4 legs in the SMA connector you pictured? They are not there to make a pretty picture! They are there to go through matching holes in the circuit board and connect to the board ground and be soldered in place to make the connector stable.
In addition, the patch antenna also provides shielding for the circuits under it.
Perhaps you need to remove the patch antenna and see what is under it.
Have you checked Sparkfun's offerings? Those are all guaranteed original manufacturer.
If I want to connect an active antenna, I don't know if 1 wire is enough?
It is (plus ground) but an appropriate power interface circuit with DC blocking receiver coupling is required. Check Sparkfun's schematic diagrams for examples.
You will see that pin 14 (VCC_RF) is used to supply power to the active antenna, through resistor R14 and inductor FB2. C1 is used to decouple this supply.
On the PCB you showed in post #1, I don't see any sign of those components. So there would be no power available to power an active antenna.
Look how the 4 pins of the SMA connector are attached to the GND on both sides of the PCB.
There is a calculation shown in the top left hand corner about the characteristic impedance of the stripline used to connect the antenna. It is important to have this correct.
