LinHT Rev B – GNSS antenna issues

Vlastimil OK5VAS recently tested the GNSS module. Unfortunately, the module used (Quectel LG77L) does not obtain a fix, even when enabled for 30 minutes, outdoors.

The most suspicious part, and likely culprit, is the path between the antenna and the module:

When measured, S11 (from the GNSS module’s perspective) looks like this:

Many thanks to Martin OK1WPM, who helped measure the antenna path both with the cover removed and with the chassis held in place.

A quick ad hoc fix before Friedrichshafen ham fair is to place an additional capacitor along the coplanar waveguide:

Some more experimentation is required. Keep your fingers crossed! See you in Germany!