Site Planning
Choosing locations and understanding what affects coverage.

Choosing a Repeater Location
Location is the single most important factor in a repeater's effectiveness. A mediocre antenna on a perfect hilltop will outperform an excellent antenna at ground level every time.
Elevation is everything
At 915 MHz, radio waves travel essentially in straight lines (line-of-sight), with only limited diffraction around obstacles. The higher your repeater, the farther it can see before the curvature of the earth and obstacles block the signal. Greater height extends the radio horizon, though the gain per additional meter diminishes — range scales with the square root of height, so doubling antenna height does not double range.
Location types - best to acceptable
Hilltops and ridgelines
The gold standard. A repeater on a hilltop with unobstructed 360-degree views dramatically extends coverage beyond ground level — typically on the order of 10-20 km (6-12 miles) to handheld nodes, and farther node-to-node when both ends are elevated with clear line of sight. Longer links of 20+ miles are achievable only under ideal, full line-of-sight conditions between two well-elevated stations; that is a best-case radio horizon, not a guaranteed coverage radius to ground-level clients, and real coverage is usually less. Use a link-budget or viewshed tool to estimate realistically and verify with field tests. Even a modest hill of 100 - 200 feet above the surrounding terrain makes a significant difference.
Rooftops
Excellent for urban and suburban coverage. The highest accessible rooftop in a neighborhood, mounted on a pole or parapet wall, provides clear line-of-sight in most directions.
Communications and water towers
Already optimized for radio coverage. Many amateur radio operators and property owners are open to hosting community infrastructure. Never climb a communications or water tower without the owner's explicit authorization — doing so is often illegal, and such towers carry high-power RF emitters and electrical hazards. Arrange access and any mounting work through the tower owner and a qualified climber.
Tall trees
A practical option for rural or forested areas. Safety first: work at height on a tree or mast carries a serious fall risk — use proper fall-protection gear or hire a qualified climber, and never free-climb. Keep all masts and the antenna well clear of power lines. Mount as high as you can safely and legally reach, and ensure the solar panel receives adequate sunlight throughout the day.
Balconies and upper-floor windows
The minimum viable option when rooftop access is unavailable. Orient toward the direction offering the clearest line of sight. Even a second-floor position is meaningfully better than ground level.
What to avoid
 
Low ground - valleys and depressions block signal in nearly all directions
 
Dense tree cover at antenna level - foliage attenuates 915 MHz signals through absorption and scattering (roughly 0.2-0.5 dB/m of vegetation at 900 MHz, and more when wet); keep the antenna above the canopy
 
Large metal structures nearby - HVAC equipment and metal roofing reflect and detune signals
 
Fully indoor placement - walls absorb a significant fraction of signal strength
Testing before committing
Before a permanent installation, test with a temporary mount. Walk around the intended coverage area while watching signal on a paired phone. Tools like HeyWhatsThat can help visualize the theoretical radio horizon from a given point, though they do not account for buildings or vegetation.

Antenna Selection and Mounting
The antenna matters more than the radio
For a fixed repeater, the antenna is often the most impactful upgrade available. Moving from a 2 dBi stock antenna to a 6 dBi vertical on a rooftop pole adds about 4 dB of antenna gain, though some of that is offset by the feedline loss of the longer coax run a rooftop mount requires - so net gain at the antenna is usually less than 4 dB. The larger benefit is typically the improved line-of-sight from height, not the antenna gain alone. Note that higher gain comes with a narrower vertical pattern, which can create a dead zone directly below the antenna (see the omnidirectional notes below). Mounting safety: work on a roof or mast with fall protection, and keep the mast clear of overhead power lines by at least its full length plus a safety margin.
Antenna types for repeaters
Omnidirectional vertical (most common)
Radiates equally in all directions horizontally - ideal for a repeater that needs to serve a wide area. Higher gain (dBi) concentrates the signal closer to the horizontal plane, extending horizontal range but reducing coverage of areas directly below. As a general rule of thumb, moderate gain (roughly 3 - 6 dBi) is commonly a good balance for elevated repeaters; very high gain can starve coverage below the site. Very high gain antennas can create a dead zone directly beneath them.
Directional (Yagi, patch)
Focuses energy in one direction for maximum reach between two specific points. Requires careful aiming and is not suitable for general area coverage.
Gain vs. coverage angle
The figures below are general guidance, not fixed specifications - the right choice depends on your site, terrain, and mounting height.
Gain
Horizontal range
Best use
2 - 3 dBi
Short
Ground-level or indoor use
5 - 6 dBi
Medium - long
Most rooftop repeaters
8 - 9 dBi
Long, narrow beam
Tall towers over flat terrain (the narrow vertical beam needs height and level ground to avoid undershooting or overshooting on hills)
FCC compliance note: In the 902 - 928 MHz band, antennas above 6 dBi require an equal dB reduction in conducted transmit power under 47 CFR 15.247(b)(4). The maximum legal EIRP works out to 36 dBm (4 W). There is no 915 MHz point-to-point gain exemption (that applies only to 2.4 / 5.8 GHz). Plan power and antenna gain together.
Cable quality
Coaxial cable losses are significant at 915 MHz. RG-58 loses roughly 0.5 dB/m and even LMR-200 is about 0.33 dB/m - not truly low-loss for long runs. Keep the run as short as possible regardless of cable type. For runs beyond a few meters, use genuine low-loss cable in the LMR-240 / LMR-400 class (LMR-400 is about 0.11 dB/m); LMR-200 is acceptable only for very short runs. Weatherproof all outdoor connector joins with self-amalgamating tape or appropriate connector covers.
Key mounting rules
 
Mount the antenna as high as practical, clear of obstructions in all directions. Use fall protection when working at height, and keep the mast clear of overhead power lines by its full length plus a margin.
 
Keep the cable run short - locate the radio enclosure close to the antenna rather than running a long cable
 
Use stainless steel hardware outdoors to prevent rust. Galvanic corrosion specifically occurs between dissimilar metals, so matching or electrically isolating the metals at a joint also matters.
 
For a fixed outdoor antenna, bond and ground the installation per NEC Article 810.
 
Don't transmit without an antenna connected - it's good practice to keep one attached. (The SX1262 used in these radios is fairly mismatch-tolerant, so a brief accidental transmit into an open connector is unlikely to destroy it; the risk of permanent damage from a mismatch is more relevant to high-power PA/FEM builds.)