A well-placed antenna is essential for achieving good RTK positioning results.
You can place your smartphone near the window in your house and it will obtain GPS coordinates after some time, but for RTK such environment won't be sufficient. For RTK to work there are special requirements for antenna placement.
Clear sky view without obstacles¶
An antenna needs to have a clear sky view 30 degrees above the horizon. There should be no obstacles that could block the view like buildings, trees, cars, humans, laptops, etc.
Examples of good environments for antenna placement:
top of the hill
Examples of bad environments for antenna placement:
close to the ground
No electronics nearby¶
Electronic devices may produce RF noise that could affect the reception of the GPS signal. Keep all electronics (including the Reach M+ itself) as far as possible from the antenna.
An antenna has to be placed on a ground plane which reduces multipath, provides shielding and improves signal reception. A ground plane is a conductive plate, it may be a piece of metal, a roof of a car, a metal roof of a building, etc.
Tallysman TW4721 requires ground plane no less than 70x70mm.