How to Find a Good Relay Site

8 min read

Finding a good relay site is not about finding the highest mountain in the area. It’s about finding the right combination of radio horizon, accessibility, and practical sustainability. A church tower you can drive to, power reliably, and maintain with the landowner’s ongoing goodwill will do more for the network than a summit you can only reach on foot in summer.

This guide walks through how to evaluate candidate sites systematically.

Start with Coverage Gaps

Before choosing a site, understand where the network needs coverage. The network planning map shows every candidate building in Scotland scored by how much new coverage it would unlock. Red markers indicate coverage gaps — areas with no nearby active node. These are where a new relay has the highest impact.

The summit scorer ranks candidates across four dimensions:

Factor	Weight	What it measures
Coverage gap	+40	Is there already a node within radio range?
Height AGL	+30	How high above local terrain is the antenna position?
Accessibility	+20	How easy is it to reach for install and maintenance?
Structure type	+10	Church towers score highest; flat community halls score less

Use this as your starting point. A high-scoring building in a coverage gap is the network’s priority, not yours — but your ability to actually deploy and maintain something there is what makes it real.

Elevation: AGL is What Matters

The most important number is height above ground level (AGL) — specifically, how far the antenna sits above the surrounding obstacles. A node at 300m above sea level, tucked below a ridgeline, may see nothing. A node at 50m ASL on a church tower above a market town’s rooftops can reach 20+ km in every direction.

The radio horizon formula is:

d = 4.12 × √h (kilometres)

Where h is antenna height in metres AGL. For two nodes communicating, the horizons add:

Height AGL	Radio Horizon
5m	~9 km
10m	~13 km
25m	~21 km
40m	~26 km
60m	~32 km

A node at 25m AGL talking to another at 25m AGL has a combined theoretical horizon of 42 km — covering a substantial slice of Scotland’s lowlands from a single pair of church towers.

Read Why Height Matters for a full treatment of radio horizons and link budgets.

The Radio Horizon and Terrain

Height gets you above local obstacles. Terrain determines what you can actually reach from there.

Scotland’s landscape creates radio shadows. A node on the west side of a ridge has excellent coverage westward and nothing east. A node in the centre of a glen may reach 10 km along the glen axis but nothing perpendicular to it.

What to look for:

Open aspect in multiple directions. A structure with clear sky-view across 270° or more will serve the network far better than one with excellent reach in one direction and hills behind it.
No nearby ridgelines at similar or greater height. The summit that looks high on a map may sit below a plateau that blocks everything to the north.
Water bodies nearby. Sea lochs, firths, and inland lochs provide exceptional propagation paths — water is a very flat, very reflective surface for radio.
Gaps in existing node coverage. Use the planning map to identify where your candidate’s radio horizon falls in relation to current nodes. Overlapping coverage is wasted.

Practical Terrain Assessment

The network planning map uses real terrain data to show what each candidate can see. Check the candidate’s coverage radius — does it reach into the gap, or does it overlap with existing nodes?

For more detailed link analysis between two specific points, use the RF analysis tools, which run line-of-sight checks using EUDEM 25m elevation data. This lets you check whether a specific building can actually see a specific target node before you approach the landowner.

Structure Types and What They Offer

Not all elevated structures are equal. What matters is whether the antenna position is actually above the local skyline.

Church towers and steeples — Scotland’s most reliable source of relay sites. Typically 15–50m AGL above the surrounding rooftops. Spread across every town and village. Usually managed by an active congregation with a reason to engage with community projects. The session clerk (Church of Scotland) or parish administrator is normally the right first contact.

Water towers — On elevated ground at the edge of settlements by design. Typically 20–40m of structure above high ground. Scottish Water manages most; community-owned towers exist in smaller settlements. Harder to negotiate but very high-value if accessible.

Telecom masts — Already purpose-built for radio. Often on high ground with existing cable runs. Commercial operators are difficult to approach; community-owned masts (common in rural areas) are much more tractable.

Estate buildings — Shooting lodges, farm steadings, and estate outbuildings on elevated Highland ground. The estate factor or manager is your contact. Many estates are interested in community projects on their land, particularly if there’s a clear benefit to estate staff communications.

Community and civic buildings — Town halls, community centres, schools, fire stations. Accessible rooftops at 5–15m AGL. Lower impact than towers, but in coverage gaps they still matter. Council facilities teams or community trust boards are the contacts.

What to avoid:

Residential rooftops (landowner relationship is fragile; maintenance access is awkward)
Structures with no clear mounting point above parapet height
Sites with restricted access that would prevent maintenance visits

Access and Maintenance

A relay that cannot be maintained will fail. When evaluating a site, ask:

Can you get there in winter? Scotland’s high-ground tracks become impassable in snow and ice. A summit site that’s only accessible on foot six months of the year is a summer node, not a network backbone.

Can you get to the hardware once it’s installed? A node mounted on a church tower’s exterior requires roof access. A node in a locked equipment room requires a key holder. Confirm the access arrangements before committing to the site.

Who maintains the relationship? The landowner’s goodwill is the most fragile part of any installation. One unanswered message, one hardware failure that goes unfixed, one visit without notice — any of these can end the arrangement. Identify who in the community will own the relationship and the hardware before you approach anyone.

How long would a repair take? If the hardware fails at 11pm in January, what’s the realistic timeline for a fix? Remote, access-restricted sites need more robust hardware and more thorough initial installations.

Power

Power is often the deciding factor between a good site and an impractical one.

Mains power is the best option. A building with a willing landowner and a mains supply is a year-round, reliable node. Offer to cover the electricity cost (at Meshtastic’s power consumption, this is pennies per year) and the conversation becomes much simpler.

Solar is viable at most sites in Scotland with careful sizing. A 5W panel and 6,000 mAh LiFePO4 battery will sustain a Meshtastic node through Scottish winter cloudy periods if the panel has a good southern aspect. Ensure the panel mount doesn’t shadow the antenna, and that the panel is not itself shaded by the structure.

Battery-only is a maintenance burden. Monthly battery swaps are an acceptable arrangement for a trial deployment but not for a permanent relay.

What to check on site:

Is there a south-facing surface without obstruction for a panel?
Is there a mains supply the landowner might offer access to?
Where would the enclosure be mounted — is it accessible for the cable run?
Are there any metal structures (parapet rails, pipework) that might shade a solar panel or interfere with the antenna?

Building Your Shortlist

A practical approach to identifying candidate sites:

Open the network planning map. Filter to coverage gaps and sort by score. Note the top 10–15 candidates in your area.
Run a satellite view check. Google Maps satellite view shows rooftop structure in detail. Look for tower height, aspect, and any obvious obstructions. Check Street View for ground-level confirmation.
Run a line-of-sight check. Use /tools to check what the candidate site can see from existing nodes in the registry. A candidate that can’t see any existing node is a more isolated deployment — not necessarily wrong, but it means higher priority for getting neighbouring sites established too.
Confirm on the ground. Satellite imagery is good but not perfect. Before approaching anyone, visit the site. Walk around it. Look at the roofline from street level. Identify the access points. Note anything not visible from imagery — locked gates, active construction, neighbouring buildings that might block the horizon.
Approach the landowner. With a clear picture of why this specific building is valuable, your conversation is much more compelling. See the Getting Started guide for how to structure that conversation.

The Planning Map as a Living Tool

The /plan map is updated continuously as new nodes are registered and new candidates are added. If you identify a building that isn’t listed, you can add it to the candidate database via a pull request to the repository — or use the “Suggest a building” button on the site. Every community-identified candidate improves the planning tool for everyone.

Scoring is automatic. Once a candidate is in the database, the scoring system evaluates it against the current node network and flags whether it sits in a coverage gap. As the network grows, scores change — a building that scores highly today may score less once a nearby node is deployed, and a building that was low-priority may become critical if a current node goes offline.

The network is built one site at a time, by people who know their local terrain. Use the tools, check the map, and then go find the building.