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Topic: Active GPS antenna is not working (Read 135 times) previous topic - next topic

caneradiyaman6

I have decided to use Antenova product which is M20057-1 as an active GPS antenna. I am using Quectel L96 GNSS module. There is an internal chip antenna on L96 module and I have tried the performance of L96 without M20057-1 before. I have achieved to get location data while the device at outdoor but We couldn't get the location data at indoor. That's why I have decided to use an active antenna to improve performance. I have just received the PCB with M20057 and I am not able to get the location data for both indoor and outdoor with M20057-1. So It is obvious that there is problem with the design of the printed circuit board. But I don't know that the problem is matching circuit(does it affect the performance that much), layout or schematic.  So Could you please review my schematic and layout to check is there any problem? I know that it quite hard to detect the problem in this way but even your approaches might be pretty useful. I am going to share screenshots of schematics and layout. Waiting for your responses.
Best Regards.

srnet

For a short trace with an active antenna you would not expect the matching to have a majot affect, the signal from the active antenna should be at a failry high level anyway.

Apart from saying you are 'not able to get the location data' you have not said if the GPS is seeing any satellites and if so how strong the signals are, you need to know this.

If it were my layout I would not have run the serial RX and TX lines from the GPS over the antenna track.
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caneradiyaman6

#2
Nov 11, 2019, 07:50 pm Last Edit: Nov 12, 2019, 07:25 am by caneradiyaman6
For a short trace with an active antenna you would not expect the matching to have a majot affect, the signal from the active antenna should be at a failry high level anyway.
Thanks for sharing the information. Also, I am using a GSM module on my board. I haven't done anything to match the trace with the antenna and Its performance is quite good. Same thing for the BlueTooth microstrip antenna. I also expect at least to get the location when the device outside. So something is wrong with my design for sure.

Apart from saying you are 'not able to get the location data' you have not said if the GPS is seeing any satellites and if so how strong the signals are, you need to know this.
I haven't check it yet. I am going to check thanks.
If it were my layout I would not have run the serial RX and TX lines from the GPS over the antenna track.
You are right to say that. Unfortunately, I have to make the board as small as possible. This limitation pushed me do a lot of unwanted things and one of them is the one you mention. Fortunately, there is no problem for UART communication between microcontroller and GPS module. There are other things I should have avoided like via in antenna trace(cause reflection). Trace should have been straight instead of curved(I made it curved instead of using 45 angles I saw some examples like this to decrease the reflection). Also, the placement of active antenna is not that good it should be at least 10mm away from the PCB edge.   

I would like to give so more detail about the design. I have uploaded two ss to describe how i think during designing the circuit. For L96 Anton pin has been designed for decreasing active antenna power consumption. Anton pin is only pulled high when the module is high. I haven't used the Anton pin. I am using pnp mosfet circuit as a high side switch to control the power consumption of GPS module so I connect the same supply to the active antenna in this way when the module is closed active antenna is also closed. Please check the pin description and application circuit of M20057 it is written that AT1 should be connected to the ground. In my design, there are matching elements on the circuit but I haven't soldered them. After seeing this pin description I have made a short circuit AT1 to ground. I thought that was the problem but it changed anything. So should I also do the same thing for AT2? There is also another matching component that is not soldered. My deadline is on Friday. I have been working on this project for a long time I know that expecting the solution from here is a bit unfair. However I am desperate I have sent an e-mail to antenova but I am sure that It will take a lot to reach me for them. I really do not have any clue about the problem. Waiting for your valuable comments.

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