Sim868 GPS antenna tuning

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Hi.
I’m working on making a tracker with the SIM868 module from scratch. In the Hardware design guide found on the SIM868 website, it said that we need to get the values of the capacitors C101 and C102 via manual tuning.


The image given above is for the GPS design. It is the same case with GPRS and Bluetooth antennas. I couldn’t find anything regarding this anywhere on the internet. Any help with that? Do I contact the manufacturers for the values? Can I tune it on my own?
Any and all help will be greatly appreciated.

These values are given after antenna tuning process, its done by RF experts (Usually antenna manufacturers). But if you just want the circuit to work. Keep the capacitors open and use 0E resistor inplace of R101. You might get better results with a active antenna. Any reason to use a passive antenna?