How MowReview makes money: As an Amazon Associate, MowReview earns from qualifying purchases, at no extra cost to you. We don’t test mowers ourselves; we explain what manufacturers and independent testers report. How we research
Quick answer
Almost always, it’s sky view. Move the reference antenna higher and to the most open spot you have, clear of tree canopy, rooflines and large metal or glass surfaces, then remap. That one change fixes most cases. If the problem is confined to one shaded corner, mark it as a no-go zone rather than replacing the mower.
Wavy lines instead of straight ones, strips of uncut grass, a mower that pauses in the same corner, or an outright signal warning in the app: these are all the same underlying problem. Here’s how to work through it, cheapest fix first.
Nothing on this page requires a purchase.
Why it happens
RTK positioning works by comparing satellite signals at your mower against the same signals at a reference antenna in a known fixed position, which is what makes it accurate to a couple of centimeters. Both ends of that need a clear view of the sky.
Ecovacs, which sells RTK mowers itself, explains the two ways it breaks down: obstructions, where leaves, branches and trunks reduce the usable open sky, and multipath, where signals bounce off nearby metal and glass and arrive confused. A yard can be perfectly fine in March and problematic in June, once the trees are in full leaf.
Work through it in this order
1. Note exactly where it happens
Under the big tree? Down the side of the house? Everywhere? A problem confined to one area is an obstruction problem in that area. A problem everywhere points at the antenna position or the connection.
2. Check the app’s signal reading
Most apps show positioning or signal quality. Look at it while standing in the problem area, and compare with the middle of the open lawn. That confirms the diagnosis before you move anything.
3. Move the antenna (the big one)
This fixes most cases. Aim for:
- The most open sky on the property, away from tree canopy.
- Higher. Use the supplied pole or a wall bracket, and get above roof and fence lines where you can.
- Away from large metal and glass, which cause reflected-signal errors.
- Within the manual’s stated distance of the mowing area.
Moving the antenna usually means your existing map no longer lines up, so plan to remap afterwards. Photograph the new position once you’re happy with it.
4. Check the antenna is properly fixed
A pole that has worked loose, tilted or been knocked by a mower or a dog will cause exactly these symptoms. It must be rigid, upright and unmoved since mapping.
5. Update the firmware
Manufacturers do improve positioning behavior in software. Segway suggests checking for updates as part of routine maintenance, and it costs nothing to rule out.
6. Remap the affected area
If the boundary was drawn while the signal was poor, the map itself may be slightly wrong. After improving the antenna position, remap, walking slowly, especially at corners.
7. Accept the shaded corner
If one area under dense trees still won’t behave, mark it as a no-go zone and trim it yourself occasionally. That’s a far better outcome than a mower that strands itself weekly.
If your mower uses network RTK
Some models take their correction over a cellular or internet connection instead of from a yard antenna. If yours does, the questions change: check cellular coverage at the property, whether the subscription or included data period is still active, and the router or signal situation. Segway notes performance may be limited where the network signal is weak.
Symptoms and what they usually mean
| What you see | Usual cause | First thing to try |
|---|---|---|
| Wavy or crooked lines | Weak positioning while mowing | Move the antenna higher and more open |
| Uncut strips in one area | Obstruction over that area | Check sky view there; no-go zone if it persists |
| Pauses in the same corner | Local signal loss | Same as above |
| Problems everywhere, suddenly | Antenna moved, or a connection issue | Check the antenna is upright and unmoved |
| Worse in summer than spring | Trees now in full leaf | Reposition the antenna, or consider a no-go zone |
| Can’t complete mapping | Poor signal, or an app connection dropping | Improve the antenna position, then retry mapping |
If the mower is physically stranding itself rather than wandering, that’s a different problem: see robot mower keeps getting stuck.
On that last one: PCWorld hit repeated Bluetooth dropouts while mapping one mower and had to restart, so a failed map isn’t always a signal problem.
When the yard is the problem, not the setup
If your lawn sits under a closed canopy, there may be no antenna position that solves it. Satellite positioning needs sky, and mature trees don’t negotiate. In that case the honest answer is that a different kind of navigation suits your yard: laser-guided mowers navigate without satellites at all, and a boundary wire ignores the issue entirely.
Before concluding that, though, try the antenna move. It’s free, and it resolves more cases than anything else. Our guides to the RTK base station and mowers for yards with trees cover both sides of this.
Questions
Why does my robot mower cut in wavy lines?
Its position isn’t precise enough while it’s mowing, which usually means weak satellite signal. Moving the reference antenna higher and into the most open spot available is the first and most effective fix, followed by remapping.
Where exactly should the antenna go?
The most open part of the property, mounted as high as the fixing allows, clear of tree canopy and rooflines and away from large metal or glass surfaces. Obstructions reduce the usable satellite signal, and reflections cause errors. Keep it within the distance your manual specifies.
My mower worked fine in spring and struggles now. Why?
Most likely the trees. Bare branches in early spring let far more signal through than a full summer canopy over the same lawn. Repositioning the antenna helps; if one area stays problematic all summer, a no-go zone there is a reasonable compromise.
Do I need a new mower?
Usually not. Work through the antenna position, mounting, firmware and remapping first, since all of those are free. Only if your lawn has no usable sky view anywhere does the navigation type itself become the problem.
Sources
- Ecovacs: LiDAR vs. RTK robot lawn mowers (RTK accuracy, obstructions, multipath)
- Amazon listing: Segway Navimow X430 (network signal limits)
- PCWorld: Ecovacs GOAT A3000 review (mapping dropouts)
- Segway Navimow: Maintenance guidance (firmware updates)
- Husqvarna: Automower support (reference station position and boundaries)
- TechRadar: Mammotion LUBA 3 AWD 3000 review (network RTK, included data period)
