External GPS antenna on Thingy:91/PCA20035 1.4.0

Question

I received a bunch of Thingy:91/PCA20035 version 1.4.0 which upgraded the SWF connector for GPS antenna to a uFL/IPX connector which is great. I also have a few PCA20035 version 1.0.0 and the GPS fix time was horrible with the internal antenna. The documentation still mentions a SWF adapter so I guess it wasn't updated. 
 I have a few questions reguarding the use of an external antenna: 
 
 It the Errata v1.0 still valid? I guess so because the Fractus internal antenna is the same reference. 
 Do you have a suggestion for an external GPS antenna (that may fit inside the case)? I tried an active antenna but the performance is terrible.

Heidi · Accepted Answer

Here is the comment from the developer: 
 
 Basically what we did was to focus on "pre LNA" loss: 
 
 Replaced inductors with higher Q variants. 
 Removed SWF connector that was before LNA 
 Shortened the transmission lines before LNA 
 Replaced LNA with higher gain and lower noise figure. 
 Retuned the antenna after these changes was made. 
 In total we had an efficiency increase from ~20% to ~40%

Not sure we have tried any external antenna, the connection is equal to the nRF9160-DK, so the antenna following the DK should work, but it would not fit inside the casing. (Remember to keep on-board LNA disabled when testing external antenna) 
 
 The plot is from the FR01-S4-210 user manual. It is not relevant at all for the Thingy:91 performance 
 
 The measurements are done on a big evaluation board (142 x 60 mm) and with a fixed matching network 
 Thingy:91 is much smaller ~50 x 50 mm and we are doing active tuning.

Please note: We are not supporting L2, so no need to consider that band.

External GPS antenna on Thingy:91/PCA20035 1.4.0

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