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I recently made my first PCB. I ordered it from China and soldered it up on my homemade oven, and it's working awesome.

I've already started a list for rev 2. There is one issue that I'm hoping I can get some experienced advice on.

Module from uputronics My board

Here are pictures of my board, and a GPS module from Uputronics. I've done a lot of testing, and the module from uputronics is consistently better. It locks in about half the time, it picks up more satellites, and the satellites both modules pick up, the uputronics gets about 10 dB better signal.

Is there any tips or guidance I can get for how to make my GPS antenna layout better? 10 dB seems like a lot, is there some important rule that I'm overlooking? Any help I can get so I can make rev 2 of my board as good as this module would be much appreciated.

Thanks in advance.

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    \$\begingroup\$ The datasheet mentions that the antenna manufacturer will review your design for free. Might be worth trying. \$\endgroup\$ – JRE Apr 12 '18 at 15:52
  • \$\begingroup\$ Your antenna layout is a bit different. It would be better to copy the commercial module precisely in every detail if possible. Also, GPS can be sensitive to VCC ripple. What else is on the board besides GPS? \$\endgroup\$ – mkeith Feb 2 at 2:20
  • \$\begingroup\$ You didn't copy the stitch vias, and I think the geometry is different. Your trace is skinnier, and the GND plane does not extend as far from the GPS module. \$\endgroup\$ – mkeith Feb 2 at 2:22
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You are not tuning the antenne. Since you have cut away the PCB around the antenne, it makes no sence to compare the two designs. You need to implement some kind of tuning, using a VNA to analyse the antenne and bring its impedance to match 50 ohm.

This whitepaper from Nordic describes it in detail. http://infocenter.nordicsemi.com/pdf/nwp_017.pdf

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In the datasheet you'll find layouting strategies and recommendations for the best operation of the device.

Usually they referr to the absence of a ground plane under and around the antenna and even a board cutout (as can be seen on the second picture you provided)

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  • \$\begingroup\$ Here is the datasheet: johansontechnology.com/datasheets/antennas/1575AT43A0040.pdf I've tried to to everything it says, but it's not as explicit as I would like... For example, should I be putting ground vias all the way around my entire board like shown in the pictures? \$\endgroup\$ – Tarrinr Apr 12 '18 at 14:47
  • \$\begingroup\$ Yes, you should always follow as closely as you can the recommendations from the datasheets, as those are product of many test runs done by their engineers. It doesn't mention anything about a PCB cutout, and maybe they did not consider it for proper operation (at seems to be the case with you) but we can see that the other design you showed us has this cutout and is performing better. I've used other RF modules on designs and always placed a cutout around the antenna \$\endgroup\$ – Radiohead Apr 12 '18 at 14:55

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